SARS-CoV-2 Delta variant

For lineage B.1.617.1, see SARS-CoV-2 Kappa variant.

SARS-CoV-2 Variant
Scientifically accurate atomic model of the external structure of SARS-CoV-2. Each "ball" is an atom.
Scientifically accurate atomic model of the external structure of SARS-CoV-2. Each "ball" is an atom.
General details
Symptoms
Major variants
  • BA.1 (B.1.1.529.1)
  • BA.2 (B.1.1.529.2)
  • BA.3 (B.1.1.529.3)
  • BA.4 (B.1.1.529.4)
  • BA.5 (B.1.1.529.5)
Part of a series on the
COVID-19 pandemic
Scientifically accurate atomic model of the external structure of SARS-CoV-2. Each "ball" is an atom.
Scientifically accurate atomic model of the external structure of SARS-CoV-2. Each "ball" is an atom.
Timeline
2019
2020
  • January
    • responses
  • February
    • responses
  • March
    • responses
  • April
    • responses
  • May
    • responses
  • June
    • responses
  • July
    • responses
  • August
    • responses
  • September
    • responses
  • October
    • responses
  • November
    • responses
  • December
    • responses
2021
2022
2023
Locations
By country and territory
By conveyance
International response
National responses
Medical response
Vaccines
Current vaccines
Variants
Variants of concern
Other variants
Economic impact and recession
By country
By sport
  • Association football
  • Baseball
  • Basketball
  • Combat sports
  • Cricket
  • Disc golf
  • Gaelic games
  • Gridiron football
  • Ice hockey
  • Motorsport
  • Rugby league
Impacts
Society

The Delta variant (B.1.617.2) was[3][4] a variant of SARS-CoV-2, the virus that causes COVID-19. It was first detected in India on 5 October 2020. The Delta variant was named on 31 May 2021 and had spread to over 179 countries by 22 November 2021. The World Health Organization (WHO) indicated in June 2021 that the Delta variant was becoming the dominant strain globally.[5]

It has mutations in the gene encoding the SARS-CoV-2 spike protein[6] causing the substitutions T478K, P681R and L452R,[7][8] which are known to affect transmissibility of the virus as well as whether it can be neutralised by antibodies for previously circulating variants of the COVID-19 virus.[9] In August 2021, Public Health England (PHE) reported secondary attack rate in household contacts of non-travel or unknown cases for Delta to be 10.8% vis-à-vis 10.2% for the Alpha variant;[10] the case fatality rate for those 386,835 people with Delta is 0.3%, where 46% of the cases and 6% of the deaths are unvaccinated and below 50 years old.[11] Immunity from previous recovery[12][13] or COVID-19 vaccines are effective in preventing severe disease or hospitalisation from infection with the variant.[14]

On 7 May 2021, PHE changed their classification of lineage B.1.617.2 from a variant under investigation (VUI) to a variant of concern (VOC) based on an assessment of transmissibility being at least equivalent to B.1.1.7 (Alpha variant);[15] the UK's SAGE using May data estimated a "realistic" possibility of being 50% more transmissible.[16] On 11 May 2021, the WHO also classified this lineage VOC, and said that it showed evidence of higher transmissibility and reduced neutralisation. On 15 June 2021, the Centers for Disease Control and Prevention (CDC) declared Delta a variant of concern.[17]

The variant is thought to be partly responsible for India's deadly second wave of the pandemic beginning in February 2021.[18][19][20] It later contributed to a third wave in Fiji, the United Kingdom[21][22][23] and South Africa,[24] and the WHO warned in July 2021 that it could have a similar effect elsewhere in Europe and Africa.[25][24] By late July, it had also driven an increase in daily infections in parts of Asia,[26] the United States,[27] Australia, and New Zealand.[28]

Classification

a-d)Schematic diagram and 3D surface structural model shows different significant mutations position in the S-glycoprotein of Delta variant of SARS-CoV-2.

The Delta variant has mutations in the gene encoding the SARS-CoV-2 spike protein[6] causing the substitutions D614G, T478K, P681R and L452R.[29][8] It is identified as the 21A, 21I, and 21J clades under the Nextstrain phylogenetic classification system.[30]

Names

The virus has also been referred to by the term "Indian Variant"[31] as it was originally detected in India. However, the Delta variant is only one of three variants of the lineage B.1.617, all of which were first detected in India.[32] At the end of May 2021, the WHO assigned the label Delta to lineage B.1.617.2 after introducing a new policy of using Greek letters for variants of concern and variants of interest.[33]

Other sublineages of B.1.617

There are three sublineages of lineage B.1.617 categorised so far.

B.1.617.1 (Kappa variant) was designated a Variant Under Investigation in April 2021 by Public Health England. Later in April 2021, two other variants B.1.617.2 and B.1.617.3 were designated as Variants Under Investigation. While B.1.617.3 shares the L452R and E484Q mutations found in B.1.617.1, B.1.617.2 lacks the E484Q mutation. B.1.617.2 has the T478K mutation, not found in B.1.617.1 and B.1.617.3.[34][35] Simultaneously, the ECDC released a brief maintaining all three sublineages of B.1.617 as VOI, estimating that a "greater understanding of the risks related to these B.1.617 lineages is needed before any modification of current measures can be considered".[36]

Mutations

The Delta/ B.1.617.2 genome has 13 mutations (15 or 17 according to some sources, depending on whether more common mutations are included) which produce alterations in the amino-acid sequences of the proteins it encodes.[37]

The list of spike protein mutations is: 19R, (G142D), Δ156-157, R158G, L452R, T478K, D614G, P681R, D950N according to GVN,[38] or T19R, G142D, del 156–157, R158G, L452R, T478K, D614G, P681R according to Genscript[39] Four of them, all of which are in the virus's spike protein code, are of particular concern:

  • D614G. The substitution at position 614, an aspartic acid-to-glycine substitution, is shared with other highly transmissible variants like Alpha, Beta and Gamma.[9]
  • T478K.[9][29] The exchange at position 478 is a threonine-to-lysine substitution.[40]
  • L452R. The substitution at position 452, a leucine-to-arginine substitution, confers stronger affinity of the spike protein for the ACE2 receptor[41] and decreased recognition capability of the immune system.[8][42]
  • P681R. The substitution at position 681, a proline-to-arginine substitution, which, according to William A. Haseltine, may boost cell-level infectivity of the variant "by facilitating cleavage of the S precursor protein to the active S1/S2 configuration".[43]

The E484Q mutation is not present in the B.1.617.2 genome.[43][44]

  • Amino acid mutations of SARS-CoV-2 Delta variant plotted on a genome map of SARS-CoV-2 with a focus on Spike.
    Amino acid mutations of SARS-CoV-2 Delta variant plotted on a genome map of SARS-CoV-2 with a focus on Spike.[45]
Defining mutations in the
SARS-CoV-2 Delta variant
Gene Nucleotide Amino acid
ORF1b P314L
P1000L
Spike G142D
T19R
R158G
L452R
T478K
D614G
P681R
D950N
E156del
F157del
M I82T
N D63G
R203M
D377Y
ORF3a S26L
ORF7a V82A
T120I
Sources: CDC[46] Covariants.org[47]

Lineages

As of August 2021, Delta variants have been subdivided in the Pango lineage designation system into variants from AY.1 to AY.28. However, there is no information on whether such classification correlates with biological characteristic changes of the virus.[48] It is said that, as of August 2021, AY.4 to AY.11 are predominant in the UK, AY.12 in Israel, AY.2, AY.3, AY.13, AY.14, AY.25 in the US, AY.20 in the US and Mexico, AY.15 in Canada, AY.16 in Kenya, AY.17 in Ireland and Northern Ireland, AY.19 in South Africa, AY.21 in Italy and Switzerland, AY.22 in Portugal, AY.24 in Indonesia, and AY.23 in Indonesia, Singapore, Japan, and South Korea.[49]

"Delta plus" variant

See also: Variants of SARS-CoV-2 § Delta (lineage B.1.617.2)

Delta with K417N originally corresponded to lineages AY.1 and AY.2,[50] subsequently also lineage AY.3,[51] and has been nicknamed "Delta plus" or "Nepal variant".[52] It has the K417N mutation,[53] which is also present in the Beta variant.[54] The exchange at position 417 is a lysine-to-asparagine substitution.[55]

As of mid-October 2021, the AY.3 variant accounted for a cumulative prevalence of approximately 5% in the United States, and 2% worldwide.[56] In mid-October the AY.4.2 Delta sublineage was expanding in England, and being monitored and assessed. It contains mutations A222V and Y145H in its spike protein,[57] not considered of particular concern. It has been suggested that AY.4.2 might be 10-15% more transmissible than the original Delta variant. Mid-October 2021, AY.4.2 accounted for an estimated 10% of cases, and has led to an additional growth rate rising to about 1% (10% of 10%) per generational time of five days or so. This additional growth rate would grow with increasing prevalence. Without AY.4.2 and no other changes, the number of cases in the UK would have been about 10% lower.[58] AY.4.2 grows about 15% faster per week.[59] In the UK it was reclassified as a "variant under investigation" (but not "of concern") in late October 2021.[60] In Denmark, after a drop in AY.4.2 cases, a new fast surge was detected and monitored, but was not yet considered a cause of concern.[61][62]

Symptoms

Main article: Symptoms of COVID-19

The most common symptoms may have changed from the most common symptoms previously associated with standard COVID-19. Infected people may mistake the symptoms for a bad cold and not realize they need to isolate. Common symptoms reported have been headaches, sore throat, a runny nose or a fever.[1][2] In the United Kingdom, when the Delta variant accounted for 91 percent of new cases, one study found that the most reported symptoms were headache, sore throat, and runny nose.[63]

Prevention

See also: COVID-19 § Prevention, Oxford–AstraZeneca COVID-19 vaccine § Effectiveness, Pfizer–BioNTech COVID-19 vaccine § Effectiveness, Moderna COVID-19 vaccine § Effectiveness, Janssen COVID-19 vaccine § Clinical trials, Sinopharm BIBP COVID-19 vaccine § Variants, Sputnik V COVID-19 vaccine § Effectiveness, CoronaVac § Variants, Covaxin § Efficacy, ZF2001 § Efficacy, and Abdala (vaccine) § Efficacy
Summary of vaccine protection against Delta
(WHO's update, 24 August 2021[64])
Disease or infection Severe: protection retained
Symptomatic: possibly reduced protection
Severe disease Steady: AstraZeneca-Vaxzevria(1), Moderna(1), Pfizer-BioNTech(2)
Symptomatic disease Steady to Neutral decrease: Pfizer-BioNTech(3)
Neutral decrease: Covaxin(1)
Neutral decreaseNeutral decrease: AstraZeneca-Vaxzevria(2)
Infection Neutral decrease: AstraZeneca-Vaxzevria(1), Pfizer-BioNTech(1)
Symbols indicate the magnitude of vaccine effectiveness (VE) reduction. Note that VE reduction doesn't mean loss of protection, because original high protection rate (such as 95%) with some reduction (such as 10%) would still retain protection (such as 85%). Enclosed in parentheses is the number of studies supporting the indication. Studies vary in population, outcome definitions, study design, etc., which may explain differences in VE estimates for a product in different studies. Also, the reductions represent VE estimates and do not represent uncertainties around the estimates which may vary substantially across studies. The VE reductions should be interpreted with these limitations.

Steady: VE reduces <10%, or VE >90% without comparator
Neutral decrease: VE reduces between 10 and <20%

Neutral decreaseNeutral decrease: VE reduces between 20 and <30%
Effects on neutralization (fully vaccinated)[65]
Steady to Neutral decrease: Anhui-ZIFIVAX(2), Covaxin(3)
Neutral decrease: Janssen(3), Moderna(3), Covishield(2)
Neutral decrease to Neutral decreaseNeutral decrease: AstraZeneca-Vaxzevria(4), Pfizer-BioNTech(8)
Neutral decreaseNeutral decrease:Moderna & Pfizer-BioNTech(1)*
Neutral decrease to Neutral decreaseNeutral decreaseNeutral decrease: Coronavac(2)
Symbols indicate the magnitude of neutralization reduction with full vaccination. Enclosed in parentheses is the number of studies supporting the indication.

Steady: Neutralization reduces <2-fold
Neutral decrease: Neutralization reduces 2 to <5-fold
Neutral decreaseNeutral decrease: Neutralization reduces 5 to <10-fold
Neutral decreaseNeutral decreaseNeutral decrease: Neutralization reduces ≥ 10-fold
* Moderna & Pfizer-BioNTech were evaluated together.

WHO has not issued preventative measures against Delta specifically; non-pharmaceutical measures recommended to prevent wild type COVID-19 should still be effective. These would include washing hands, wearing a mask, maintaining distance from others, avoiding touching the mouth, nose or eyes, avoiding crowded indoor spaces with poor ventilation especially where people are talking, going to get tested if one develops symptoms and isolating if one becomes sick.[66] Public Health authorities should continue to find infected individuals using testing, trace their contacts, and isolate those who have tested positive or been exposed.[67] Event organizers should assess the potential risks of any mass gathering and develop a plan to mitigate these risks.[68] See also Non-pharmaceutical intervention (epidemiology).

ICMR found that convalescent sera of the COVID-19 cases and recipients of Bharat Biotech's BBV152 (Covaxin) were able to neutralise VUI B.1.617 although with a lower efficacy.[69]

Anurag Agrawal, the director of the Institute of Genomics and Integrative Biology (IGIB), said the study on the effectiveness of the available vaccines on lineage B.1.617 suggests that post-vaccination, the infections are milder.[70]

Anthony Fauci, the Chief Medical Advisor to the President of the United States, has also expressed his confidence regarding the preliminary results. In an interview on 28 April, he said:

This is something where we're still gaining data daily. But the most recent data was looking at convalescent sera of COVID-19 cases and people who received the vaccine used in India, the Covaxin. It was found to neutralise the 617 variants.[71]

Another study by the Centre for Cellular and Molecular Biology (CCMB) in Hyderabad found Covishield (Oxford–AstraZeneca) vaccinated sera offers protection against lineage B.1.617.[72]

A study conducted by the Public Health England, has found that compared to those who were unvaccinated those who were vaccinated with either the Pfizer-BioNTech or AstraZeneca-Oxford had 33% less instances of symptomatic disease caused by the variant after the first dose. Among those who were two weeks after the receiving their second dose of the Pfizer-BioNTech vaccine 88% less subjects had symptomatic disease from the Delta variant versus those that were unvaccinated. Among those who were two weeks after the receiving their second dose of the AstraZeneca-Oxford vaccine 60% less subjects had symptomatic disease from the Delta variant versus those that were unvaccinated.[73][74]

A study by a group of researchers from the Francis Crick Institute, published in The Lancet, shows that humans fully vaccinated with the Pfizer-BioNTech vaccine are likely to have more than five times lower levels of neutralizing antibodies against the Delta variant compared to the original COVID-19 strain.[75][76]

In June 2021, Public Health England announced it had conducted a study which found that after two shots, the Pfizer-BioNTech vaccine and the AstraZeneca vaccine are respectively 96% and 92% effective at preventing hospitalisation from the Delta variant.[77][78]

On July 3, researchers from the universities of Toronto and Ottawa in Ontario, Canada, released a preprint study suggesting that the Moderna vaccine may be effective against death or hospitalization from the Delta variant.[79]

In a study of the University of Sri Jayewardenepura in July 2021 found the Sinopharm BIBP vaccine caused seroconversion in 95% of individuals studied that had received both doses of the vaccine. The rate was higher in 20-39 age group (98.9%) but slightly lower in the over 60 age group (93.3%). Neutralising antibodies were present among 81.25% of the vaccinated individuals studied.[80][81]

On 29 June 2021, the director of the Gamaleya Institute, Denis Logunov, said that Sputnik V is about 90% effective against the Delta variant.[82]

On July 21, researchers from Public Health England published a study finding that the Pfizer vaccine was 93.7% effective against symptomatic disease from Delta after 2 doses, while the Astrazeneca vaccine was 67% effective.[83]

On August 2, several experts expressed concern that achieving herd immunity may not currently be possible because the Delta variant is transmitted among those immunized with current vaccines.[84]

On August 10, a study showed that the full vaccination coverage rate is correlated inversely to the SARS-CoV-2 delta variant mutation frequency in 16 countries (R-squared=0.878). Data strongly indicates that full vaccination against COVID-19 may slow down virus evolution.[85]

Treatment

See also: Treatment and management of COVID-19

In vitro experiments suggest that bamlanivimab may not be effective against Delta on its own.[86] At high enough concentrations, casirivimab, etesevimab and imdevimab appear to still be effective. A preprint study suggests that sotrovimab may also be effective against Delta.[87] Doctors in Singapore have been using supplemental oxygen, remdesivir and corticosteroids on more Delta patients than they did on previous variants.[88]

Epidemiology

Summary of impacts for Delta*
(WHO's update, 24 August 2021[64])
Transmissibility Increased transmissibility and secondary attack rate, similar transmissibility between vaccinated and unvaccinated individuals.
Virulence Increased risk of hospitalization
Reinfection Decreased neutralizing activity
Diagnostics No impacts yet reported
* Generalized finding compared to other strains, based on evidence including non-peer-reviewed publications.

Transmissibility

UK scientists have said that the Delta variant is between 40% and 60% more transmissible than the previously dominant Alpha variant, which was first identified in the UK (as the Kent variant).[89] Given that Alpha is already 150% as transmissible as the original SARS-CoV-2 strain that emerged in late 2019 in Wuhan,[89] and if Delta is 150% as transmissible as Alpha, then Delta may be 225% as transmissible as the original strain.[90] BBC reported that  – basic reproduction number, or the expected number of cases directly generated by one case in a population where all individuals are susceptible to infection – for the first detected SARS-CoV-2 virus is 2.4–2.6, whereas Alpha's reproduction number is 4–5 and Delta's is 5–9.[91][92] These basic reproduction numbers can be compared to MERS (0.29-0.80[93]), seasonal influenza (1.2–1.4[94]), Ebola (1.4–1.8[95]), common cold (2–3[96]), SARS (2–4[97]), smallpox (3.5–6[98]), and chickenpox (10–12[99]). Due to Delta's high transmissibility even those that are vaccinated are vulnerable,[100] albeit to a lesser extent.[74]

A study[101] published online (not peer-reviewed) by Guangdong Provincial Center for Disease Control and Prevention may partly explain the increased transmissibility: people with infection caused by Delta had 1,000 times more copies of the virus in the respiratory tracts than those with infection caused by variants first identified in the beginning of the pandemic; and it took on average 4 days for people infected with Delta for the virus to be detectable compared to 6 days with initially identified variants.[102][103]

Surveillance data from the U.S., Germany and the Netherlands indicates the Delta variant is growing by about a factor of 4 every two weeks with respect to the Alpha variant.[104][105][106]

In India, the United Kingdom,[107] Portugal,[108] Russia,[109] Mexico, Australia, Indonesia,[110] South Africa, Germany,[111] Luxembourg,[112] the United States,[113] the Netherlands,[114] Denmark,[115] France[116] and probably many other countries, the Delta variant had become the dominant strain by July 2021. Depending on country, there is typically a lag from a few days to several weeks between cases and variant reporting. As of July 20, this variant had spread to 124 countries,[65] and WHO had indicated that it was becoming the dominant strain, if not one already.[117]

In the Netherlands, the virus was still able to propagate significantly in the population with over 93.4% of blood donors being tested positive for SARS-CoV-2 antibodies after week 28, 2021. Many people there are not fully vaccinated, so those antibodies would have been developed from exposure to the wild virus or from a vaccine.[118][119] Similar high seroimmunity levels occur in the United Kingdom in blood donors and general surveillance.[120][121][122]

A preprint found that the viral load in the first positive test of infections with the variant was on average ∼1000 times higher than with compared infections during 2020.[123][124] Preliminary data from a study with 100,000 volunteers in the UK from May to July 2021, when Delta was spreading rapidly, indicates that vaccinated people who test positive for COVID-19, including asymptomatic cases, have a lower viral load in average. Data from the US, UK, and Singapore indicate that vaccinated people infected by Delta may have viral loads as high as unvaccinated infected people, but might remain infectious for a shorter period.[125]

Infection age groups

Surveillance data from the Indian government's Integrated Disease Surveillance Programme (IDSP) shows that around 32% of patients, both hospitalised and outside hospitals, were aged below 30 in the second wave compared to 31% during the first wave, among people aged 30–40 the infection rate stayed at 21%. Hospitalisation in the 20–39 bracket increased to 25.5% from 23.7% while the 0–19 range increased to 5.8% from 4.2%. The data also showed a higher proportion of asymptomatic patients were admitted during the second wave, with more complaints of breathlessness.[126]

Virulence

See also: Virulence

A few early studies suggest the Delta variant causes more severe illness than other strains.[127] On 7 June 2021, researchers at the National Centre for Infectious Diseases in Singapore posted a paper suggesting that patients testing positive for Delta are more likely to develop pneumonia and/or require oxygen than patients with wild type or Alpha.[128] On June 11, Public Health England released a report finding that there was "significantly increased risk of hospitalization" from Delta as compared with Alpha;[129] the risk was approximately twice as high for those infected with the Delta variant.[130] On June 14, researchers from Public Health Scotland found that the risk of hospitalization from Delta was roughly double that of from Alpha.[131] On July 7, a preprint study from epidemiologists at the University of Toronto found that Delta had a 120% greater – or more than twice as large – risk of hospitalization, 287% greater risk of ICU admission and 137% greater risk of death compared to non-variant of concern strains of SARS-COV-2.[132] However, on July 9, Public Health England reported that the Delta variant in England had a case fatality rate (CFR) of 0.2%, while the Alpha variant's case fatality rate was 1.9%, although the report warns that "case fatality rates are not comparable across variants as they have peaked at different points in the pandemic, and so vary in background hospital pressure, vaccination availability and rates and case profiles, treatment options, and impact of reporting delay, among other factors."[133] James McCreadie, a spokesperson for Public Health England, clarified "It is too early to assess the case fatality ratio compared to other variants."[134]

A Canadian study released on 5 October 2021 revealed that the Delta variant caused a 108 percent rise in hospitalization, 235 percent increase in ICU admission, and a 133 percent surge in death compared to other variants. is more serious and resulted in an increased risk of death compared to previous variants, odds that are significantly decreased with immunization.[135][136]

Statistics

The chance of detecting a Delta case varies significantly, especially depending on a country's sequencing rate (less than 0.05% of all COVID-19 cases have been sequenced in the lowest-sequencing countries to around 50 percent in the highest).[137][138]

By 22 June 2021, more than 4,500 sequences of the variant had been detected in about 78 countries.[139][140][141] Reported numbers of sequences in countries with detections are:

Cases by country
Country/Area Confirmed cases (PANGOLIN)[142]
as of 19 December		 Confirmed cases (GISAID)[139]
as of 23 November		 Cases (other sources)
as of 19 January 2022		 First detection Last detection
Template:Flagu/core 985,491826,4651,625,557[143]22 February 2021
Template:Flagu/core 1,099,811947,47299.4% of cases[144]23 February 2021
Template:Flagu/core 78,41262,008196,866[145]15 March 2021
Template:Flagu/core 150,416117,5131 March 2021
Template:Flagu/core 138,33689,7068 March 2021
Template:Flagu/core 86,38370,97386,037[146] [147]28 March 2021
Template:Flagu/core 75,22470,82221 February 2021
Template:Flagu/core 54,13450,5785[148]28 April 2021
Template:Flagu/core -50747,639 [149][150][151]19 April 2021
Template:Flagu/core 45,63845,0555 October 2020
Template:Flagu/core 48,30438,00329 March 2021
Template:Flagu/core 46,01837,77326 March 2021
Template:Flagu/core 37,33431,61125 March 2021
Template:Flagu/core 33,64229,2822 April 2021
Template:Flagu/core 30,61828,25722 April 2021
Template:Flagu/core 33,12827,8706 April 2021
Template:Flagu/core 23,69622,71525,750[152]16 March 2021
Template:Flagu/core 22,42521,06126 February 2021
Template:Flagu/core 27,73317,9871051 [153][154]20 May 2021[155][156][157][158][159]
Template:Flagu/core 20,23017,7105 April 2021
Template:Flagu/core 16,33413,43920 April 2021
Template:Flagu/core 15,78712,25941[160][161][162]16 April 2021
Template:Flagu/core 15,71612,1301[163]15 April 2021
Template:Flagu/core 12,98411,9835 April 2021
Template:Flagu/core 2,58210,6194[164]30 April 2021
Template:Flagu/core 16,48410,32016[165]26 April 2021
Template:Flagu/core 8999,0701[166]17 June 2021
Template:Flagu/core 1,5708,7332,876[167][168][169][170]18 March 2021
Template:Flagu/core 11,2258,48724 April 2021
Template:Flagu/core 2,7277,51026 February 2021
Template:Flagu/core 3537,14615 June 2021
Template:Flagu/core 8703,2208,612[171][172]11 May 2021
Template:Flagu/core 7066,49726 March 2021
Template:Flagu/core 4796,16511 June 2021
Template:Flagu/core 645,85813 June 2021
Template:Flagu/core 1,1535,51515 April 2021
Template:Flagu/core 1,6234,9803 April 2021
Template:Flagu/core 2944,65526 April 2021
Template:Flagu/core 2314,6145 April 2021
Template:Flagu/core 1,4684,29516[173]21 April 2021
Template:Flagu/core 2364,2932[174]24 April 2021
Template:Flagu/core -3,76730 August 2021
Template:Flagu/core 1463,62410 April 2021
Template:Flagu/core 1,5783,62217 April 2021
Template:Flagu/core 922,844107[175][176]9 March 2021
Template:Flagu/core -2,74021 July 2021
Template:Flagu/core 172,64223 March 2021
Template:Flagu/core 62,58010 June 2021
Template:Flagu/core 1172,0135 April 2021
Template:Flagu/core 361,7951[177]7 August 2021
Template:Flagu/core 2561,7005[177][178]17 July 2021
Template:Country data Aruba 901,59216 April 2021
Template:Flagu/core 541,41412[179][180]18 April 2021
Template:Country data Puerto Rico -1,3609 September 2021
Template:Flagu/core 1211,34319 April 2021
Template:Flagu/core 2831,2739[181][182]28 April 2021
Template:Flagu/core -1,23119 March 2021
Template:Flagu/core 891,02320 July 2021
Template:Flagu/core 1179841[183]30 April 2021
Template:Flagu/core -9743 July 2021
Template:Country data Botswana 1969122[184]28 April 2021
Template:Country data Gibraltar -8485 September 2021
Template:Flagu/core -8342 May 2021
  1. REDIRECT Template:Country data Réunion
547544 May 2021
Template:Flagu/core 1717335 April 2021
Template:Flagu/core -71710 August 2021
Template:Flagu/core 356897 July 2021
Template:Flagu/core 4967616 May 2021
Template:Flagu/core 8653624 April 2021
Template:Country data Maldives 652531 July 2021
Template:Flagu/core 10152220 April 2021
  1. REDIRECT Template:Country data Curaçao
-46723 April 2021
Template:Flagu/core -45813 July 2021
Template:Flagu/core 3143026 July 2021
Template:Flagu/core -42416 August 2021
Template:Country data Seychelles -40730 September 2021
Template:Flagu/core 43852[185]24 April 2021
Template:Country data Martinique 836510 August 2021
Template:Country data Guadeloupe -36210 March 2021
Template:Flagu/core 536021 April 2021
Template:Flagu/core 1343401[186]26 March 2021
Template:Flagu/core 8232629 May 2021
Template:Country data Gambia 4231612 July 2021
Template:Flagu/core -31416 July 2021
Template:Flagu/core 430229 July 2021
Template:Flagu/core 912839 July 2021
Template:Country data Cameroon -28228 September 2021
Template:Flagu/core 1927215 May 2021
Template:Country data French Guiana 5326422 July 2021
Template:Country data U.S. Virgin Islands -24718 August 2021
Template:Country data Nepal 1002389[187]28 April 2021
Template:Flagu/core 192285[177]3 May 2021
Template:Country data Malawi 521330 April 2021
Template:Flagu/core 1081915 June 2021
Template:Flagu/core -1788 August 2021
Template:Flagu/core 1317024 June 2021
Template:Flagu/core -16719 August 2021
Template:Flagu/core 815917 May 2021
Template:Flagu/core 615914 January 2021
Template:Flagu/core 1531022 April 2021
Template:Country data Suriname -1503 August 2021
Template:Flagu/core 31382[188] 3 May 2021
Template:Country data Togo -13031 July 2021
Template:Flagu/core -1143 August 2021
Template:Flagu/core -110June 2021
Template:Flagu/core 41008 July 2021
Template:Country data Belize -9830 June 2021
Template:Flagu/core -9815 July 2021
Template:Country data Zimbabwe -9626 July 2021
Template:Country data Liechtenstein -9515 July 2021
Template:Flagu/core 13936 May 2021
  1. REDIRECT Template:Country data Republic of the Congo
-8715 July 2021
Template:Flagu/core -8619 July 2021
Template:Country data Eswatini -8126 July 2021
Template:Flagu/core -803 July 2021
Template:Flagu/core 227327 May 2021
Template:Country data Monaco 347015 May 2021
Template:Country data Mauritius 15678 May 2021
Template:Country data Malta 426323 June 2021
Template:Country data Guinea-Bissau -623 November 2021
Template:Country data Burundi 35731 May 2021
Template:Country data Antigua and Barbuda -576 August 2021
Template:Country data Liberia -5610 July 2021
Template:Flagu/core -505 August 2021
Template:Flagu/core 3047(number unreported)[189]25 June 2021
Template:Country data Benin -4723 July 2021
Template:Flagu/core 63811 July 2021
  1. REDIRECT Template:Country data Bahamas
-388 August 2021
Template:Flagu/core -3730 July 2021
Template:Flagu/core 12331 June 2021
Template:Flagu/core 5336 July 2021
  1. REDIRECT Template:Country data East Timor


  • From a page move: This is a redirect from a page that has been moved (renamed) or is the result of a page move. One reason this page was kept as a redirect is to avoid breaking links, both internal and external, that may have been made to the old page name. Any redirect with a page move logged on its history page should be tagged with this rcat template.
 -3312[190]8 August 2021
Template:Country data South Sudan -297 June 2021
Template:Flagu/core -2823 June 2021
Template:Country data Brunei -2817 August 2021
Template:Flagu/core -272 August 2021
Template:Country data Mayotte -2721 October 2021
Template:Flagu/core 17256[191]28 July 2021
Template:Country data Andorra -2517 July 2021
Template:Country data Barbados 32324 May 2021
Template:Country data Sierra Leone -228 September 2021
Template:Flagu/core 11213[192]11 May 2021
Template:Flagu/core -2121 April 2021
Template:Flagu/core -211 July 2021
Template:Flagu/core -2024 May 2021
Template:Country data Northern Mariana Islands 2197 July 2021
Template:Country data Central African Republic -1714 August 2021
Template:Flagu/core 31514 June 2021
Template:Country data Guam -1426 April 2021
Template:Country data Dominican Republic -143 May 2021
Template:Flagu/core --14[193]22 July 2021
Template:Flagu/core -1430 August 2021
Template:Flagu/core 21327 April 2021
Template:Flagu/core 11116 July 2021
Template:Flagu/core 111113 July 2021
Template:Country data Comoros -1126 October 2021
Template:Flagu/core -1023 July 2021
Template:Country data Anguilla -820 April 2021
Template:Flagu/core -726 July 2021
Template:Country data Montserrat -71 August 2021
Template:Flagu/core -717 August 2021
Template:Country data British Virgin Islands -527 July 2021
Template:Flagu/core -14[194]19 May 2021
Template:Country data Turks and Caicos Islands -412 July 2021
Template:Flagu/core -214 July 2021
Template:Flagu/core -231 July 2021
Template:Flagu/core -22 August 2021
Template:Country data Saint Vincent and the Grenadines -28 August 2021
Template:Flagu/core -211 August 2021
Template:Flagu/core -29 September 2021
Template:Country data Haiti -1(number unreported)[189]27 July 2021
Template:Flagu/core -11[195]29 April 2021
Template:Flagu/core -121 May 2021
Template:Flagu/core -17 July 2021
Template:Flagu/core -17 July 2021
Template:Flagu/core -123 September 2021
Template:Flagu/core --(number unreported)[189]16 May 2021[189]
 World (178 countries) Total: 3,119,592
(solely B.1.617.2)		Total: 2,768,050
(B.1.617.2+AY.1+AY.2+AY.3)		Total: 1,862,122

History

The first cases of the variant outside India were detected in late February 2021, including the United Kingdom on 22 February, the United States on 23 February and Singapore on 26 February.[196][37][139]

British scientists at Public Health England redesignated the B.1.617.2 variant on 7 May 2021 as "variant of concern" (VOC-21APR-02),[197] after they flagged evidence in May 2021 that it spreads more quickly than the original version of the virus.[21] Another reason was that they identified 48 clusters of B.1.617.2, some of which revealed a degree of community transmission.[198][199] With cases from the Delta variant having risen quickly, British scientists considered the Delta variant having overtaken the Alpha variant as the dominant variant of SARS-CoV-2 in the UK in early June 2021.[200] Researchers at Public Health England later found that over 90% of new cases in the UK in the early part of June 2021 were the Delta variant; they also cited evidence that the Delta variant was associated with an approximately 60% increased risk of household transmission compared to the Alpha variant.[201]

Canada's first confirmed case of the variant was identified in Quebec on 21 April 2021, and later the same day 39 cases of the variant were identified in British Columbia.[202] Alberta reported a single case of the variant on 22 April 2021.[203] Nova Scotia reported two Delta variant cases in June 2021.[204]

Fiji also confirmed its first case of the variant on 19 April 2021 in Lautoka, and has since then climbed up to 47,000 cases and counting.[205] The variant has been identified as a super-spreader and has led to the lockdowns of five cities (Lautoka, Nadi, Suva, Lami and Nausori), an area which accounts for almost two-thirds of the country's population.

On 29 April 2021, health officials from Finland's Ministry of Social Affairs and Health (STM) and the Finnish Institute for Health and Welfare (THL) reported that the variant had been detected in three samples dating back to March 2021.[167]

The Philippines confirmed its first two cases of the variant on 11 May 2021, despite the imposed travel ban of the country from the nations in the Indian subcontinent (except for Bhutan and Maldives). Both patients have no travel history from India for the past 14 days, but instead from Oman and UAE.[206]

North Macedonia confirmed its first case of the variant on 7 June 2021 after a person who was recovering from the virus in Iraq was transported to North Macedonia. In a laboratory test, the variant was detected in the person. On 22 June 2021, the country reported its second case of the Delta variant in a colleague of the first case who had also been in Iraq and who subsequently developed symptoms.[207]

The detection of B.1.617 was hampered in some countries by a lack of specialised kits for the variant and laboratories that can perform the genetic test.[208][209] For example, as of 18 May, Pakistan had not reported any cases, but authorities noted that 15% of COVID-19 samples in the country were of an "unknown variant"; they could not say if it was B.1.617 because they were unable to test for it. Other countries had reported travellers arriving from Pakistan that were infected with B.1.617.[208]

In June 2021, scientist Vinod Scaria of India's Institute of Genomics and Integrative Biology highlighted the existence of the B.1.617.2.1 variant, also known as AY.1 or Delta plus, which has an additional K417N mutation compared to the Delta variant.[53] B.1.617.2.1 was detected in Europe in March 2021, and has since been detected in Asia and America.[53]

On 23 June 2021, the European Centre for Disease Prevention and Control (ECDC) warned that the variant would represent 90% of all new cases in the European Union by the end of August.[210]

By 3 July 2021, Delta became dominant in the US.[211]

On 9 July 2021, Public Health England issued Technical Briefing 18 on SARS-CoV-2 variants, documenting 112 deaths among 45,136 UK cases of SARS-CoV-2 Delta variant with 28 days follow-up with a fatality rate of 0.2%.[212] Briefing 16 notes that "[M]ortality is a lagged indicator, which means that the number of cases who have completed 28 days of follow up is very low – therefore, it is too early to provide a formal assessment of the case fatality of Delta, stratified by age, compared to other variants."[213] Briefing 18 warns that "Case fatality is not comparable across variants as they have peaked at different points in the pandemic, and so vary in background hospital pressure, vaccination availability and rates and case profiles, treatment options, and impact of reporting delay, among other factors."[212] The most concerning issue is the logistic growth rate of 0.93/week relative to Alpha. This means that per week, the number of Delta samples/cases is growing by a factor of exp (0.93)=2.5 with respect to the Alpha variant. This results, under the same infection prevention measures, in a much greater case load over time until a large fraction of people have been infected by it.[214][215]

Government responses

After the rise in cases from the second wave, at least 20 countries imposed travel bans and restrictions on passengers from India in April and May. UK prime minister Boris Johnson cancelled his visit to India twice, while Japanese Prime Minister Yoshihide Suga postponed his April trip.[216][217][218]

In May 2021, residents of two tower blocks in Velbert, Germany, were quarantined after a woman in the building tested positive for the Delta variant.[219]

In May, Delhi Chief Minister Arvind Kejriwal said that a new coronavirus variant from Singapore was extremely dangerous for children and could result in a third wave in India.

From 16 May to 13 June 2021, as well as 22 July 2021 to 10 August 2021; Singapore entered lockdowns, known as "Phase 2 Heightened Alert", similar to 2020.

On 14 June, the British prime minister Boris Johnson announced that the proposed end of all restrictions on 21 June in the United Kingdom was delayed for up to four weeks and vaccination roll-out was accelerated following concerns over the Delta variant, which accounted for the vast majority (90%) of new infections.[220] UK scientists have said that the Delta variant is between 40% and 60% more transmissible than the previously dominant Alpha variant, which was first identified in the UK (as the Kent variant).[221]

On 23 June, the province of Ontario in Canada accelerated 2nd dose vaccine appointments for people living in Delta hot spots such as Toronto, Peel and Hamilton.[222]

On 25 June, Israel restored their mask mandate citing the threat of Delta.[223]

On 28 June, Sydney and Darwin went back into lockdown because of Delta outbreaks.[224] South Africa banned indoor and outdoor gatherings apart from funerals, imposed a curfew, and banned the sale of alcohol.[225]

On 3 July, the islands of Bali and Java in Indonesia went into emergency lockdown.[226]

On 8 July, Japanese Prime Minister Yoshihide Suga announced that Tokyo would once again enter a state of emergency, and that most spectators would be barred from attending the Olympics set to start there on 23 July.[227]

On 9 July, Seoul, South Korea ramped up restrictions urging people to wear masks outdoors, and limiting the size of gatherings.[228]

On 12 July, French President Emmanuel Macron announced that all health care workers will need to be vaccinated by 15 September and that France will start using health passports to enter bars, cafés, restaurants and shopping centres from August.[229]

Los Angeles announced it will require masks indoors starting 17 July 2021.[230]

The United Kingdom lifted most COVID-19 restrictions on 19 July, despite a surge in cases as the Delta variant became dominant. The government cited the protection and wide coverage of the COVID-19 vaccination programme, although health experts expressed concern at the move.[231][232]

On 23 July, Vietnam extended its lockdown of Ho Chi Minh City to 1 August, and announced lockdown restrictions would be put in place in Hanoi, affecting a third of the country's population. The Delta variant had brought upon the country's largest outbreak to date, after mostly successful containment measures throughout 2020.[233][234]

On 17 August, New Zealand went into an alert level 4 lockdown, following a positive case being reported in Auckland. More cases soon followed in the Coromandel Peninsula.[235] This was the first reported community transmission case in the country in 170 days (since February 2021).[236]

Extinction

In October 2021, Dr Jenny Harries, chief executive of the UK Health and Security Agency stated that previous circulating variants such as Alpha had 'disappeared' and replaced by the Delta variant.[237] In March 2022, the World Health Organization listed the Alpha, Beta and Gamma variants as previously circulating citing lack of any detected cases in the prior weeks and months, in part due to the dominance of the Delta variant and subsequent Omicron variant.[238] However within a few months the Delta variant was listed as a previously circulated variant with countries such as Australia going 12 weeks without any detections of Delta.[4]

See also

Notes

    References

    1. 1 2 3 4 5 Grover, Natalie (14 June 2021). "Delta variant Covid symptoms 'include headaches, sore throat and runny nose'". The Guardian. London. Archived from the original on 14 June 2021. Retrieved 30 June 2021.
    2. 1 2 3 Roberts, Michelle (14 June 2021). "Headache and runny nose linked to Delta variant". BBC News. London. Archived from the original on 14 June 2021. Retrieved 2 July 2021.
    3. ↑ "Tracking SARS-CoV-2 variants". www.who.int. Archived from the original on 9 June 2021. Retrieved 17 August 2022.
    4. 1 2 "Variants of concern". CDGN. Archived from the original on 13 July 2021. Retrieved 17 August 2022.
    5. ↑ Lovelace, Berkeley Jr. (18 June 2021). "WHO says delta is becoming the dominant Covid variant globally". CNBC. Archived from the original on 4 November 2021. Retrieved 1 November 2021.
    6. 1 2 Shang, Jian; Yushun, Wan; Lou, Chuming; Ye, Gang; Geng, Qibin; Auerbach, Ashley; Fang, Li (2020). "Cell entry mechanisms of SARS-CoV-2". Proceedings of the National Academy of Sciences. 117 (21): 11727–11734. Bibcode:2020PNAS..11711727S. doi:10.1073/pnas.2003138117. PMC 7260975. PMID 32376634.
    7. ↑ "expert reaction to VUI-21APR-02/B.1.617.2 being classified by PHE as a variant of concern". sciencemediacentre.org. 7 May 2021. Archived from the original on 13 July 2021. Retrieved 18 June 2021.
    8. 1 2 3 Starr, Tyler N.; Greaney, Allison J.; Dingens, Adam S.; Bloom, Jesse D. (April 2021). "Complete map of SARS-CoV-2 RBD mutations that escape the monoclonal antibody LY-CoV555 and its cocktail with LY-CoV016". Cell Reports Medicine. 2 (4): 100255. doi:10.1016/j.xcrm.2021.100255. PMC 8020059. PMID 33842902.
    9. 1 2 3 "SARS-CoV-2 variants of concern as of 24 May 2021". European Centre for Disease Prevention and Control. Archived from the original on 16 June 2021. Retrieved 6 August 2021.
    10. ↑ "Technical Briefing 20 SARS-CoV-2 variants of concern and variants under investigation in England" (PDF). 6 August 2021. Archived (PDF) from the original on 15 December 2021. Retrieved 10 April 2023. This article contains OGL licensed text This article incorporates text published under the British Open Government Licence v3.0:
    11. ↑ "Technical Briefing 21 SARS-CoV-2 variants of concern and variants under investigation in England" (PDF). Public Health England. 20 August 2021. Archived (PDF) from the original on 23 July 2021. Retrieved 10 April 2023. This article contains OGL licensed text This article incorporates text published under the British Open Government Licence v3.0:
    12. ↑ Sivan Gazit (25 August 2021). "Comparing SARS-CoV-2 natural immunity to vaccine-induced immunity: reinfections versus breakthrough infections" (PDF). doi:10.1101/2021.08.24.21262415. S2CID 237289842. Archived (PDF) from the original on 28 August 2021. Retrieved 10 April 2023. {{cite journal}}: Cite journal requires |journal= (help) The study in Israel tracked 46035 unvaccinated recovered and 46035 vaccinated people of the same age distribution, to compare their infection occurrence in the follow-up period. 640 infections and 21 hospitalization in the vaccinated group and 108 infections and 4 hospitalizations in the recovered group were recorded.
    13. ↑ "Past Covid-19 reduces risk of reinfection from Delta variant more than Pfizer vaccine". Bloomberg. 27 August 2021. Archived from the original on 21 October 2021. Retrieved 10 April 2023.
    14. ↑ Burn-Murdoch, John; Mancini, Donato Paolo (9 July 2021). "How effective are coronavirus vaccines against the Delta variant?". www.ft.com. Archived from the original on 20 December 2021. Retrieved 23 July 2021.
    15. ↑ "Confirmed cases of COVID-19 variants identified in UK". www.gov.uk. 7 May 2021. Archived from the original on 7 May 2021. Retrieved 7 May 2021. This article contains OGL licensed text This article incorporates text published under the British Open Government Licence v3.0:
    16. ↑ "Is The Variant From India The Most Contagious Coronavirus Mutant On The Planet?". NPR. 14 May 2021. Archived from the original on 2 August 2021. Retrieved 10 April 2023. cited "Eighty-ninth SAGE meeting on COVID-19, 13 May 2021 (Held via Video Teleconference)" (PDF). UK Government. 13 May 2021. Archived (PDF) from the original on 16 May 2021. Retrieved 10 April 2023.
    17. ↑ "06/15/2021: Lab Advisory: CDC Classifies SARS-CoV-2 Variant B.1.617.2 (Delta) a Variant of Concern". CDC. 15 June 2021. Archived from the original on 9 July 2021. Retrieved 10 April 2023.
    18. ↑ WHO labels a Covid strain in India as a 'variant of concern' — here's what we know Archived 1 June 2021 at the Wayback Machine, CNBC, 11 May 2021.
    19. ↑ "WHO says India Covid variant of 'global concern'" Archived 29 May 2021 at the Wayback Machine, BBC News, 11 May 2021.
    20. ↑ Narang, Deepanshu. "COVID-19: The Second Wave May Not Be the Last – but Which One Will Be? – The Wire Science". Archived from the original on 15 May 2021. Retrieved 20 May 2022.
    21. 1 2 Mishra, Swapnil; Mindermann, Sören; Sharma, Mrinank; Whittaker, Charles; Mellan, Thomas A.; Wilton, Thomas; Klapsa, Dimitra; Mate, Ryan; Fritzsche, Martin; Zambon, Maria; Ahuja, Janvi (1 September 2021). "Changing composition of SARS-CoV-2 lineages and rise of Delta variant in England". eClinicalMedicine. 39: 101064. doi:10.1016/j.eclinm.2021.101064. ISSN 2589-5370. PMC 8349999. PMID 34401689.
    22. ↑ Callaway, Ewen (22 June 2021). "Delta coronavirus variant: scientists brace for impact". Nature. 595 (7865): 17–18. Bibcode:2021Natur.595...17C. doi:10.1038/d41586-021-01696-3. PMID 34158664. S2CID 235609029.
    23. ↑ Rob Picheta (30 June 2021). "Britain thinks it can out-vaccinate the Delta variant. The world isn't so sure". CNN. Archived from the original on 1 July 2021. Retrieved 2 July 2021.
    24. 1 2 "Health service buckling as third coronavirus wave fuelled by Delta variant sweeps across South Africa". the Guardian. 4 July 2021. Archived from the original on 7 July 2021. Retrieved 7 July 2021.
    25. ↑ Ellyatt, Holly (1 July 2021). "New Covid wave could be imminent as delta variant sweeps Europe, WHO says". CNBC. Archived from the original on 2 July 2021. Retrieved 2 July 2021.
    26. ↑ "Delta variant: Which Asian countries are seeing rising cases?". BBC News. 19 July 2021. Archived from the original on 2 November 2021. Retrieved 23 July 2021.
    27. ↑ "US in 'another pivotal moment' as Delta variant drives surge in Covid cases". the Guardian. 23 July 2021. Archived from the original on 22 October 2021. Retrieved 23 July 2021.
    28. ↑ "New Zealand suspends quarantine-free travel bubble with Australia". ITV News. 23 July 2021. Archived from the original on 25 November 2021. Retrieved 23 July 2021.
    29. 1 2 "SARS-CoV-2 Variant Classifications and Definitions". CDC.gov. Centers for Disease Control and Prevention. 11 February 2020. Archived from the original on 16 June 2021. Retrieved 15 June 2021.
    30. ↑ "Genomic epidemiology of novel coronavirus - Global subsampling (Filtered to B.1.617)". nextstrain.org. Archived from the original on 13 July 2021. Retrieved 5 May 2021.
    31. ↑ "Covid Indian variant: Where is it, how does it spread and is it more infectious?". bbc.com. 7 June 2021. Archived from the original on 12 November 2021. Retrieved 10 April 2023.
    32. ↑ "Weekly epidemiological update on COVID-19 - 27 April 2021" (PDF). World Health Organization. 27 April 2021. Archived (PDF) from the original on 23 June 2021. Retrieved 7 September 2021.
    33. ↑ "Covid: WHO renames UK and other variants with Greek letters". BBC News. 31 May 2021. Archived from the original on 31 May 2021. Retrieved 8 June 2021.
    34. ↑ "SARS-CoV-2 Variant Classifications and Definitions". Centers for Disease Control and Prevention. 12 May 2021. Archived from the original on 16 June 2021. Retrieved 16 May 2021.
    35. ↑ Di Giacomo, Simone; Mercatelli, Daniele; Rakhimov, Amir; Giorgi, Federico M. (2021). "Preliminary report on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Spike mutation T478K". Journal of Medical Virology. 93 (9): 5638–5643. doi:10.1002/jmv.27062. PMC 8242375. PMID 33951211.
    36. ↑ "Threat Assessment Brief: Emergence of SARS-CoV-2 B.1.617 variants in India and situation in the EU/EEA". European Centre for Disease Prevention and Control. 11 May 2021. Archived from the original on 17 May 2021. Retrieved 17 May 2021.
    37. 1 2 "Expert reaction to cases of variant B.1.617 (the 'Indian variant') being investigated in the UK". Science Media Centre. Archived from the original on 14 May 2021. Retrieved 20 April 2021.
    38. ↑ "Delta (B.1.617.2) - GVN". 10 May 2021. Archived from the original on 20 December 2021. Retrieved 27 November 2021.
    39. ↑ "SARS-CoV-2 Spike protein (S1, T19R, G142D, del 156-157, R158G, L452R, T478K, D614G, P681R, His Tag) - Genscript". Archived from the original on 29 November 2021. Retrieved 28 November 2021.
    40. ↑ Greenwood, Michael (30 March 2021). "SARS-CoV-2 mutation T478K spreading at alarming speed in Mexico". Medical News. Archived from the original on 9 July 2021. Retrieved 15 June 2021.
    41. ↑ South, Andrew M.; Diz, Debra I.; Chappell, Mark C. (1 May 2020). "COVID-19, ACE2, and the cardiovascular consequences". American Journal of Physiology. Heart and Circulatory Physiology. 318 (5): H1084–H1090. doi:10.1152/ajpheart.00217.2020. PMC 7191628. PMID 32228252.
    42. ↑ Zhang, Wenjuan; Davis, Brian D.; Chen, Stephanie S.; Sincuir Martinez, Jorge M.; Plummer, Jasmine T.; Vail, Eric (6 April 2021). "Emergence of a Novel SARS-CoV-2 Variant in Southern California". JAMA. 325 (13): 1324–1326. doi:10.1001/jama.2021.1612. PMC 7879386. PMID 33571356.
    43. 1 2 Haseltine, William. "An Indian SARS-CoV-2 Variant Lands In California. More Danger Ahead?". Forbes. Archived from the original on 13 April 2021. Retrieved 20 April 2021.
    44. ↑ Hoffmann, Markus; Hofmann-Winkler, Heike; Krüger, Nadine; Kempf, Amy; Nehlmeier, Inga; Graichen, Luise; Arora, Prerna; Sidarovich, Anzhalika; Moldenhauer, Anna-Sophie; Winkler, Martin S.; Schulz, Sebastian; Jäck, Hans-Martin; Stankov, Metodi V.; Behrens, Georg M.N.; Pöhlmann, Stefan (June 2021). "SARS-CoV-2 variant B.1.617 is resistant to Bamlanivimab and evades antibodies induced by infection and vaccination". Cell Reports. 36 (3): 109415. doi:10.1016/j.celrep.2021.109415. ISSN 2211-1247. PMC 8238662. PMID 34270919. Collectively, our study reveals that antibody evasion of B.1.617 may contribute to the rapid spread of this variant... ...The RBD of the B.1.617 S protein harbors two mutations associated with (L452R) or suspected (E484Q) of antibody evasion... ...Moreover, E484K present the B.1.351 and P.1 variants confers antibody resistance (Li et al., 2021) and one could speculate that exchange E484Q might have a similar effect.
    45. ↑ Spike Variants: Delta variant, aka B.1.617.2 Archived 30 June 2021 at the Wayback Machine 24 June 2021, covdb.stanford.edu, accessed 1 July 2021
    46. ↑ "SARS-CoV-2 Variant Classifications and Definitions". cdc.gov. Centers for Disease Control and Prevention. 15 June 2021. Archived from the original on 16 June 2021. Retrieved 18 June 2021.
    47. ↑ "Dedicated 21A.S.478K Nextstrain build". covariants.org. 15 June 2021. Archived from the original on 24 June 2021. Retrieved 19 June 2021.
    48. ↑ "感染・伝播性の増加や抗原性の変化が懸念される 新型コロナウイルス（SARS-CoV-2）の新規変異株について （第13報）" [Infection: New variant of coronavirus (SARS-CoV-2): concerns as to increased infectivity / transmission and changes in antigenicity]. niid.go.jp (in Japanese). National Institute of Infectious Diseases (NIID). 28 August 2021. Archived from the original on 3 September 2021. Retrieved 5 September 2021.{{cite web}}: CS1 maint: unrecognized language (link)
    49. ↑ "New AY lineages and an update to AY.4-AY.12". pango.network. PANGO Network. 27 August 2021. Archived from the original on 26 November 2021. Retrieved 5 September 2021.
    50. ↑ SARS-CoV-2 variants of concern and variants under investigation in England, technical briefing 16 (PDF) (Briefing). Public Health England. 18 June 2021. GOV-8641. Retrieved 23 June 2021.
    51. ↑ "CDPHE to update variant data to align with CDC". Colorado Department of Public Health and Environment. State of Colorado. 17 August 2021. Archived from the original on 27 October 2021. Retrieved 25 October 2021. AY.1, AY.2, and AY.3 -- commonly referred to as delta plus
    52. ↑ Cutler, S (18 June 2021). "'Nepal variant': what we've learned so far". The Conversation. Archived from the original on 18 June 2021. Retrieved 6 August 2021.
    53. 1 2 3 "Delta plus: New Covid variant identified, experts say no cause of concern for now". The Indian Express. Press Trust of India. 14 June 2021. Archived from the original on 24 June 2021. Retrieved 23 June 2021.
    54. ↑ Sample, Ian (3 June 2021). "Nepal Covid variant: does it exist and should we be concerned?". The Guardian. Archived from the original on 23 June 2021. Retrieved 23 June 2021.
    55. ↑ Tang, Julian W.; Oliver, T.R. (2021). "Introduction of the South African SARS-CoV-2 variant 501Y.V2 into the UK". The Journal of Infection. 82 (4): e8–e10. doi:10.1016/j.jinf.2021.01.007. ISSN 0163-4453. PMC 7813514. PMID 33472093.
    56. ↑ "AY.3 Lineage Report". outbreak.info. Archived from the original on 20 July 2021. Retrieved 10 April 2023. Updates constantly.
    57. ↑ "SARS-CoV-2 variants of concern and variants under investigation in England Technical briefing 25" (PDF). UK Health Security Agency. 15 October 2021. Archived (PDF) from the original on 24 November 2021. Retrieved 26 October 2021.
    58. ↑ Davis, Nicola (19 October 2021). "Offshoot of Covid Delta variant on the rise in England". The Guardian. Archived from the original on 25 November 2021. Retrieved 10 April 2023.
    59. ↑ "SARS-CoV-2 variants of concern and variants under investigation in England: technical briefing 29" (PDF). GOV.UK. Archived (PDF) from the original on 27 November 2021. Retrieved 30 October 2021.
    60. ↑ Roberts, Michelle (22 October 2021). "Delta 'Plus' Covid variant may be more transmissible". BBC News. Archived from the original on 17 December 2021. Retrieved 10 April 2023.
    61. ↑ name. "Den nye Delta-undervariant AY.4.2 viser ikke tegn på nedsat vaccineeffektivitet". www.ssi.dk (in dansk). Archived from the original on 30 November 2021. Retrieved 14 November 2021.
    62. ↑ "outbreak.info". outbreak.info. Archived from the original on 14 November 2021. Retrieved 14 November 2021.
    63. ↑ Radcliffe, Shawn (14 June 2021). "The COVID-19 Delta Variant: Here's Everything You Need to Know". Healthline. Archived from the original on 20 August 2021. Retrieved 2 July 2021.
    64. 1 2 "Weekly epidemiological update on COVID-19 – 24 August 2021". World Health Organization. 24 August 2021. Archived from the original on 18 November 2021. Retrieved 10 April 2023.
    65. 1 2 "Weekly epidemiological update on COVID-19 - 20 July 2021". World Health Organization. 20 July 2021. Archived from the original on 23 July 2021. Retrieved 10 April 2023.
    66. ↑ "Advice for Public". WHO. Archived from the original on 26 January 2020. Retrieved 14 July 2021.
    67. ↑ "Health Workers and Administrators". WHO. Archived from the original on 13 August 2021. Retrieved 14 July 2021.
    68. ↑ "Key planning recommendations for mass gatherings in the context of the current COVID-19 outbreak". WHO. Archived from the original on 26 November 2021. Retrieved 14 July 2021.
    69. ↑ Yadav, PD; Sapkal, GN; Abraham, P; Ella, R; Deshpande, G; Patil, DY; et al. (7 May 2021). "Neutralization of variant under investigation B.1.617 with sera of BBV152 vaccinees". Clinical Infectious Diseases. 74 (2): 366–368. doi:10.1093/cid/ciab411. PMID 33961693.
    70. ↑ "Covishield Covaxin effective against 'Indian strain' of coronavirus study suggests". The Week. Archived from the original on 12 August 2021. Retrieved 27 April 2021.
    71. ↑ "Covaxin found to neutralise 617 variant of COVID-19, says Dr. Fauci". The Hindu. 28 April 2021. Archived from the original on 12 August 2021. Retrieved 10 April 2023.
    72. ↑ "Covishield, Covaxin effective against 'Indian strain' of coronavirus, study suggests - ET HealthWorld". ETHealthworld.com. The Economic Times. 28 April 2021. Archived from the original on 28 April 2021. Retrieved 10 April 2023.
    73. ↑ Ellyatt, Holly (24 May 2021). "Two doses of Covid vaccines provide effective protection against variant found in India: Study". CNBC. Archived from the original on 8 July 2021. Retrieved 10 April 2023.
    74. 1 2 Bernal, Jamie Lopez; Andrews, Nick; Gower, Charlotte; Gallagher, Eileen; Simmons, Ruth; Thelwall, Simon; et al. (24 May 2021). "Effectiveness of COVID-19 vaccines against the B.1.617.2 variant". medRxiv. doi:10.1101/2021.05.22.21257658. S2CID 235152312. Archived from the original on 20 August 2021. Retrieved 10 April 2023.
    75. ↑ Wall, Emma C; Wu, Mary; Harvey, Ruth; Kelly, Gavin; Warchal, Scott; Sawyer, Chelsea; et al. (June 2021). "Neutralising antibody activity against SARS-CoV-2 VOCs B.1.617.2 and B.1.351 by BNT162b2 vaccination". The Lancet. 397 (10292): 2331–2333. doi:10.1016/s0140-6736(21)01290-3. ISSN 0140-6736. PMC 8175044. PMID 34090624. Archived from the original on 13 July 2021. Retrieved 10 April 2023.
    76. ↑ "COVID-19 vaccine: Pfizer jabs not the best for Delta variant, says Lancet study". The New Indian Express. 5 June 2021. Archived from the original on 6 June 2021. Retrieved 10 April 2023.
    77. ↑ "Vaccines highly effective against hospitalisation from Delta variant". www.gov.uk. Public Health England. 14 June 2021. Archived from the original on 20 June 2021. Retrieved 10 April 2023. This article contains OGL licensed text This article incorporates text published under the British Open Government Licence v3.0:
    78. ↑ "UK study finds vaccines offer high protection against hospitalisation from Delta variant". Reuters. 14 June 2021. Archived from the original on 15 June 2021. Retrieved 15 June 2021.
    79. ↑ Nasreen S, He S, Chung H, Brown KA, Gubbay JB, Buchan SA, et al. (3 July 2021). "Effectiveness of COVID-19 vaccines against variants of concern, Canada". medRxiv (Preprint). doi:10.1101/2021.06.28.21259420. S2CID 235722149. Archived from the original on 16 November 2021. Retrieved 13 July 2021.
    80. ↑ "Over 95% individuals developed antibodies against the Sinopharm vaccine - USJ Researchers". USJ - University of Sri Jayewardenepura, Sri Lanka. 20 July 2021. Archived from the original on 15 October 2021. Retrieved 20 July 2021.
    81. ↑ Jeewandara, Chandima; Aberathna, Inoka Sepali; Pushpakumara, Pradeep Dharshana; Kamaladasa, Achala; Guruge, Dinuka; Jayathilaka, Deshni; Gunesekara, Banuri; Tanussiya, Shyrar; Kuruppu, Heshan; Ranasinghe, Thushali; Dayarathne, Shashika (19 July 2021). "Antibody and T cell responses to Sinopharm/BBIBP-CorV in naive and previously infected individuals in Sri Lanka". medRxiv: 2021.07.15.21260621. doi:10.1101/2021.07.15.21260621. S2CID 236039068. Archived from the original on 25 November 2021. Retrieved 10 April 2023.
    82. ↑ "Russia's Sputnik V shot around 90% effective against Delta variant, developers say". Reuters. 29 June 2021. Archived from the original on 28 July 2021. Retrieved 11 August 2021.
    83. ↑ Lopez Bernal, Jamie; Andrews, Nick; Gower, Charlotte; Gallagher, Eileen; Simmons, Ruth; Thelwall, Simon; Stowe, Julia; Tessier, Elise; Groves, Natalie; Dabrera, Gavin; Myers, Richard; Campbell, Colin N.J.; Amirthalingam, Gayatri; Edmunds, Matt; Zambon, Maria; Brown, Kevin E.; Hopkins, Susan; Chand, Meera; Ramsay, Mary (2021). "Effectiveness of Covid-19 Vaccines against the B.1.617.2 (Delta) Variant". New England Journal of Medicine. 385 (7): 585–594. doi:10.1056/NEJMoa2108891. ISSN 0028-4793. PMC 8314739. PMID 34289274.
    84. ↑ Dyer, Owen (2 August 2021). "Covid-19: Delta infections threaten herd immunity vaccine strategy". BMJ. 374: n1933. doi:10.1136/bmj.n1933. ISSN 1756-1833. PMID 34340962. S2CID 236778544. Archived from the original on 4 December 2021. Retrieved 10 April 2023.
    85. ↑ Yeh TY, Contreras, GP (10 August 2021). "Full vaccination suppresses SARS-CoV-2 delta variant mutation frequency". medRxiv. doi:10.1101/2021.08.08.21261768. S2CID 236965312. Archived from the original on 13 September 2021. Retrieved 10 April 2023.
    86. ↑ Delphine Planas (8 July 2021). "Reduced sensitivity of SARS-CoV-2 variant Delta to antibody neutralization". Nature. 596 (7871): 276–280. Bibcode:2021Natur.596..276P. doi:10.1038/s41586-021-03777-9. PMID 34237773. S2CID 235775860.
    87. ↑ Andrea Cathcart (26 July 2021). "The dual function monoclonal antibodies VIR-7831 and VIR-7832 demonstrate potent in vitro and in vivo activity against SARS-CoV-2". bioRxiv. doi:10.1101/2021.03.09.434607. S2CID 232223983. Archived from the original on 5 August 2021. Retrieved 30 July 2021.
    88. ↑ Sean Wei Xiang Ong (7 June 2021). "Clinical and Virological Features of SARS-CoV-2 Variants of Concern: A Retrospective Cohort Study Comparing B.1.1.7 (Alpha), B.1.315 (Beta), and B.1.617.2 (Delta)". SSRN 3861566.
    89. 1 2 "How Dangerous Is the Delta Variant, and Will It Cause a COVID Surge in the U.S.?". Scientific American. 29 June 2021. Archived from the original on 29 October 2021. Retrieved 10 April 2023. cited Scientific Pandemic Influenza Group on Modelling, Operational sub-group (SPI-M-O) (2 June 2021). "SPI-M-O: Consensus Statement on COVID-19" (PDF). SAGE, UK Government. Archived (PDF) from the original on 20 July 2021.{{cite web}}: CS1 maint: uses authors parameter (link)
    90. ↑ Aubrey, Allison; Simmons-Duffin, Selena (17 July 2021). "With The Delta Variant Spreading Fast, Is It Time To Mask Up Again?". NPR. Archived from the original on 2 August 2021. cited Doucleff, Michaeleen (14 May 2021). "Is The Variant From India The Most Contagious Coronavirus Mutant On The Planet?". NPR. Archived from the original on 2 August 2021.
    91. ↑ Kollmeyer, Barbara (30 July 2020). "'As transmissible as chickenpox.' Here's the CDC report on the delta variant that led to new mask policy". MarketWatch. Archived from the original on 2 August 2021. Retrieved 3 August 2021.
    92. ↑ Gallagher, James (12 June 2021). "Covid: Is there a limit to how much worse variants can get?". BBC News. Archived from the original on 3 August 2021.
    93. ↑ Kucharski AJ, Althaus CL (June 2015). "The role of superspreading in Middle East respiratory syndrome coronavirus (MERS-CoV) transmission". Euro Surveillance. 20 (25): 14–8. doi:10.2807/1560-7917.ES2015.20.25.21167. PMID 26132768.
    94. ↑ Chowell G, Miller MA, Viboud C (June 2008). "Seasonal influenza in the United States, France, and Australia: transmission and prospects for control". Epidemiology and Infection. Cambridge University Press. 136 (6): 852–64. doi:10.1017/S0950268807009144. PMC 2680121. PMID 17634159. The reproduction number across influenza seasons and countries lied in the range 0.9–2.0 with an overall mean of 1.3, and 95% confidence interval (CI) 1.2–1.4.
    95. ↑ Wong ZS, Bui CM, Chughtai AA, Macintyre CR (April 2017). "A systematic review of early modelling studies of Ebola virus disease in West Africa". Epidemiology and Infection. 145 (6): 1069–1094. doi:10.1017/S0950268817000164. PMC 9507849. PMID 28166851. The median of the R0 mean estimate for the ongoing epidemic (overall) is 1.78 (interquartile range: 1.44, 1.80) {{cite journal}}: Check |pmc= value (help)
    96. ↑ Freeman C. "Magic formula that will determine whether Ebola is beaten". The Telegraph. Telegraph.Co.Uk. Archived from the original on 11 January 2022. Retrieved 30 March 2020.
    97. ↑ Consensus document on the epidemiology of severe acute respiratory syndrome (SARS). Department of Communicable Disease Surveillance and Response (Technical report). World Health Organization. p. 26. hdl:10665/70863. WHO/CDS/CSR/GAR/2003.11. A number of researchers have estimated the basic reproduction number by fitting models to the initial growth of epidemics in a number of countries. Their observations indicate that the SARS-CoV is less transmissible than initially thought with estimates of Ro in the range of 2–4.
    98. ↑ Gani R, Leach S (December 2001). "Transmission potential of smallpox in contemporary populations". Nature. 414 (6865): 748–51. Bibcode:2001Natur.414..748G. doi:10.1038/414748a. PMID 11742399. S2CID 52799168. Archived from the original on 10 June 2020. Retrieved 18 March 2020.
    99. ↑ Ireland's Health Services. Health Care Worker Information (PDF). Archived (PDF) from the original on 26 March 2020. Retrieved 27 March 2020.
    100. ↑ Brown, Catherine M. (2021). "Outbreak of SARS-CoV-2 Infections, Including COVID-19 Vaccine Breakthrough Infections, Associated with Large Public Gatherings — Barnstable County, Massachusetts, July 2021". MMWR. Morbidity and Mortality Weekly Report. 70 (31): 1059–1062. doi:10.15585/mmwr.mm7031e2. ISSN 0149-2195. PMC 8367314. PMID 34351882.
    101. ↑ Lu, Jing (7 July 2021). "Viral infection and transmission in a large well-traced outbreak caused by the Delta SARS-CoV-2 variant". virological.org. Archived from the original on 22 July 2021.
    102. ↑ "Why The Delta Variant Is Hyper-Contagious: A New Study Sheds Light". NPR. 21 July 2021. Archived from the original on 20 December 2021. Retrieved 10 April 2023.
    103. ↑ Haseltine, William A (13 July 2021). "The Delta Dilemma: Loosening Covid-19 Controls At A Time Of Increased Danger". Forbes. Archived from the original on 3 December 2021. Retrieved 10 April 2023.
    104. ↑ "CDC covid variant tracker". 28 March 2020. Archived from the original on 24 August 2020. Retrieved 13 July 2021.
    105. ↑ "RIVM Covid variant tracker". Archived from the original on 9 July 2021. Retrieved 13 July 2021.
    106. ↑ "RKI - Coronavirus SARS-CoV-2 - Berichte zu Virusvarianten von SARS-CoV-2 in Deutschland". www.rki.de. Archived from the original on 23 June 2021. Retrieved 19 June 2021.
    107. ↑ Cave, Damien (2 July 2021). "Why the Delta Variant Could End Australia's Pursuit of 'Covid Zero'". The New York Times. Archived from the original on 8 July 2021. Retrieved 9 July 2021.
    108. ↑ Demony, Catarina (26 June 2021). "Delta variant 'spreading rapidly' from Lisbon to rest of Portugal". Reuters. Archived from the original on 28 June 2021. Retrieved 28 June 2021.
    109. ↑ "COVID-19: Russia battles Delta variant in deadly 3rd wave (video)". Deutsche Welle. 8 July 2021. Archived from the original on 9 July 2021. Retrieved 9 July 2021.
    110. ↑ Lawler, Dave (8 July 2021). "Indonesia's surging death rate underscores danger of Delta variant". Axios. Archived from the original on 17 July 2021. Retrieved 16 July 2021.
    111. ↑ "Delta-Variante dominiert in Deutschland". www.aerzteblatt.de (in Deutsch). 8 July 2021. Archived from the original on 9 July 2021. Retrieved 9 July 2021.
    112. ↑ "14 to 20 June: Delta variant dominates cases in Luxembourg with 59.4 percent". today.rtl.lu. Archived from the original on 2 July 2021. Retrieved 3 July 2021.
    113. ↑ "From UK to Indonesia: How Delta variant is dominating global Covid surge". The Times of India. 8 July 2021. Archived from the original on 16 July 2021. Retrieved 16 July 2021.
    114. ↑ "Delta variant rapidly advancing in Netherlands; Possibly caused 50% of infections". NL Times. Archived from the original on 13 July 2021. Retrieved 3 July 2021.
    115. ↑ "Risikovurdering af B.1.617.2 - opdatering" (PDF). 2 July 2021. Archived (PDF) from the original on 2 July 2021. Retrieved 10 April 2023.
    116. ↑ "Delta variant to account for most new French COVID cases from this weekend - minister". Reuters. 9 July 2021. Archived from the original on 9 July 2021. Retrieved 9 July 2021.
    117. ↑ "WHO Director-General's opening remarks at the 8th meeting of the IHR Emergency Committee on COVID-19 - 14 July 2021". WHO. 14 July 2021. Archived from the original on 15 July 2021. The Delta variant is now in more than 111 countries and we expect it to soon be the dominant COVID-19 strain circulating worldwide, if it isn't already.
    118. ↑ "Corona-antistoffen bij 93% van donors". Sanquin Netherlands (in Nederlands). Archived from the original on 27 October 2021. Retrieved 29 July 2021.
    119. ↑ "Antistoffen bij 95% van donors". Sanquin (in Nederlands). Archived from the original on 17 December 2021. Retrieved 30 October 2021.
    120. ↑ "Most Blood Donations Contain COVID-19 Antibodies". www.precisionvaccinations.com. Archived from the original on 30 October 2021. Retrieved 30 October 2021.
    121. ↑ "Coronavirus (COVID-19) latest insights - Office for National Statistics". www.ons.gov.uk. Archived from the original on 20 December 2021. Retrieved 30 October 2021.
    122. ↑ "COVID-19 vaccine surveillance report Week 43" (PDF). Archived (PDF) from the original on 15 December 2021. Retrieved 10 April 2023.
    123. ↑ Reardon, Sara (21 July 2021). "How the Delta variant achieves its ultrafast spread". Nature. doi:10.1038/d41586-021-01986-w. Archived from the original on 20 December 2021. Retrieved 13 August 2021.
    124. ↑ Li, Baisheng; et al. (23 July 2021). "Viral infection and transmission in a large, well-traced outbreak caused by the SARS-CoV-2 Delta variant". medRxiv: 2021.07.07.21260122. doi:10.1101/2021.07.07.21260122. S2CID 235794705. Archived from the original on 20 December 2021. Retrieved 13 August 2021.
    125. ↑ Subbaraman, Nidhi (12 August 2021). "How do vaccinated people spread Delta? What the science says". Nature. 596 (7872): 327–328. Bibcode:2021Natur.596..327S. doi:10.1038/d41586-021-02187-1. PMID 34385613. S2CID 236997139.
    126. ↑ Dey, Sushmi. "Covid second wave in India: Percentage of young infected in second wave same, but more serious". The Times of India. Archived from the original on 27 April 2021. Retrieved 27 April 2021.
    127. ↑ Delta Variant: What We Know About the Science Archived 21 December 2021 at the Wayback Machine, by Centers for Disease Control and Prevention
    128. ↑ Ong, Sean Wei Xiang; Chiew, Calvin J.; Ang, Li Wei; Mak, Tze-Minn; Cui, Lin; Toh, Matthias Paul HS; Lim, Yi Ding; Lee, Pei Hua; Lee, Tau Hong; Chia, Po Ying; Maurer-Stroh, Sebastian; Lin, Raymond Tzer Pin; Leo, Yee-Sin; Lee, Vernon J.; Lye, David Chien; Young, Barnaby E. (7 June 2021). "Clinical and Virological Features of SARS-CoV-2 Variants of Concern: A Retrospective Cohort Study Comparing B.1.1.7 (Alpha), B.1.315 (Beta), and B.1.617.2 (Delta)". SSRN 3861566.
    129. ↑ Public Health England (11 June 2021). "SARS-CoV-2 variants of concern and variants under investigation in England Technical briefing 15" (PDF). gov.uk. p. 50. Archived (PDF) from the original on 4 July 2021. Retrieved 22 July 2021.
    130. ↑ Twohig, Katherine A.; Nyberg, Tommy; Zaidi, Asad; Thelwall, Simon; Sinnathamby, Mary A.; Aliabadi, Shirin; Seaman, Shaun R.; Harris, Ross J.; Hope, Russell; Lopez-Bernal, Jamie; Gallagher, Eileen (27 August 2021). "Hospital admission and emergency care attendance risk for SARS-CoV-2 delta (B.1.617.2) compared with alpha (B.1.1.7) variants of concern: a cohort study". The Lancet Infectious Diseases. 22 (1): 35–42. doi:10.1016/S1473-3099(21)00475-8. ISSN 1473-3099. PMC 8397301. PMID 34461056.
    131. ↑ Sheikh, Aziz; McMenamin, Jim; Taylor, Bob; Robertson, Chris (2021). "SARS-CoV-2 Delta VOC in Scotland: demographics, risk of hospital admission, and vaccine effectiveness". The Lancet. 397 (10293): 2461–2462. doi:10.1016/S0140-6736(21)01358-1. ISSN 0140-6736. PMC 8201647. PMID 34139198.
    132. ↑ Fisman, David; Tuite, Ashleigh (12 July 2021). "Progressive Increase in Virulence of Novel SARS-CoV-2 Variants in Ontario, Canada". medRxiv. doi:10.1101/2021.07.05.21260050. S2CID 235756602. Archived from the original on 20 December 2021. Retrieved 22 July 2021.
    133. ↑ "SARS-CoV-2 variants of concern and variants under investigation in England" (PDF). assets.publishing.service.gov.uk. Public Health England Technical Briefing 18. 9 July 2021. pp. 10–11, Table 3 and footnote 2 of that table. Archived (PDF) from the original on 23 July 2021. Retrieved 19 July 2021.This article contains OGL licensed text This article incorporates text published under the British Open Government Licence v3.0:
    134. ↑ Kertscher, Tom (7 July 2021). "Data showing lower death rate for coronavirus delta variant doesn't mean it's less dangerous". Politifact. Archived from the original on 20 December 2021. Retrieved 20 July 2021.
    135. ↑ Fisman, David N.; Tuite, Ashleigh R. (4 October 2021). "Evaluation of the relative virulence of novel SARS-CoV-2 variants: a retrospective cohort study in Ontario, Canada". Canadian Medical Association Journal. 193 (42): –211248. doi:10.1503/cmaj.211248. ISSN 1488-2329. PMC 8562985. PMID 34610919.
    136. ↑ "Canadian Study Reveals Delta Lethality Higher than Original COVID - October 6, 2021". Daily News Brief. 6 October 2021. Archived from the original on 21 October 2021. Retrieved 6 October 2021.
    137. ↑ Berger, Miriam (28 November 2021). "South Africa, which found the omicron variant first, leads Africa in coronavirus sequencing". Washington Post. Archived from the original on 2 December 2021. Retrieved 2 December 2021.
    138. ↑ "Sequencing by country". GISAID. 2 December 2021. Archived from the original on 2 December 2021. Retrieved 2 December 2021.
    139. 1 2 3 "Tracking of Variants". gisaid.org. GISAID. 26 April 2021. Archived from the original on 23 June 2021. Retrieved 23 November 2021.
    140. ↑ "Weekly epidemiological update on COVID-19 - 11 May 2021". World Health Organization. 11 May 2021. Archived from the original on 11 May 2021. Retrieved 27 July 2021.
    141. ↑ "Weekly epidemiological update on COVID-19 - 22 June 2021". www.who.int. Archived from the original on 29 June 2021. Retrieved 29 June 2021.
    142. ↑ "PANGO lineages Lineage B.1.617.2". cov-lineages.org. Retrieved 19 December 2021.
    143. ↑ "COVID-19 variants: genomically confirmed case numbers". Gov.uk. Retrieved 19 December 2021.
    144. ↑ "Variant Proportions". Cdc.gov. 28 March 2020. Retrieved 30 July 2021.
    145. ↑ "Tracking variants of the novel coronavirus in Canada". Ctvnews.ca. 4 February 2021. Retrieved 19 December 2021.
    146. ↑ "Infectious Diseases Weekly Report". National Institute of Infectious Diseases. Retrieved 30 July 2021.
    147. ↑ "都道府県別の懸念される変異株の国内事例数(ゲノム解析)について". Ministry of Health, Labour and Welfare. Retrieved 30 July 2021.
    148. ↑ "Coronavirus live news, 16:54, 28 April 2021". The Guardian. 28 April 2021. Retrieved 28 April 2021.
    149. ↑ The index case of the second wave was determined to be the Delta variant. There have been over 47,000 cases originating from the index case."Fiji Ministry of Health and Medical Services COVID-19 Cases". Retrieved 5 September 2021.
    150. ↑ "Fiji COVID-19 update for 10 July 2021". Fiji Village News. 10 July 2021. Retrieved 10 July 2021.
    151. ↑ "Fiji is racing against time to vaccinate its population while a COVID-19 outbreak explodes". ABC News. 10 July 2021. Retrieved 11 July 2021.
    152. ↑ "Variants of Concern". Communicable Disease Genomes Network. Retrieved 5 December 2021.
    153. ↑ SP identifica primeiro caso de variante do coronavírus em passageiro vindo da Índia 26/05/2021 g1.globo.com, accessed 26 May 2021
    154. ↑ Covid-19: Maranhão registra primeiros casos da variante indiana 21 May 2021 pebmed.com.br, accessed 26 May 2021
    155. ↑ Barbosa, Alex (24 May 2021). "Identificação da variante indiana do coronavírus coincide com aumento de internações no Maranhão". g1.globo.com (in português do Brasil). TV Mirante e G1 MA.
    156. ↑ Coronavírus: Primeiro caso da variante indiana é confirmado no Paraná, diz Sesa (tr. "Coronavirus: First case of the Indian variant is confirmed in Paraná, says Sesa ") 02/06/2021 g1.globo.com, accessed 3 June 2021
    157. ↑ Variante delta do coronavírus é identificada e tem transmissão comunitária em Goiânia g1.globo.com, accessed 23 June 2021
    158. ↑ "Casos da variante Delta podem estar subnotificados no Brasil".
    159. ↑ "Delta: Brasil supera mil casos confirmados da variante; crescimento foi de 84% em uma semana - Saúde".
    160. ↑ Soni, Parul (30 April 2021). "Israel Is The Most Vaccinated Country, But The B.1.617 Is Threatening It Now". International Business Times. IBT Media.
    161. ↑ "Israel logs Indian COVID-19 variant, sees some vaccine efficacy against it". Reuters. 20 April 2021. Retrieved 24 April 2021.
    162. ↑ "זוהו 41 מקרים של הזן (הווריאנט) ההודי, מתוכם 24 חוזרים מחו"ל" [41 cases of the Indian variety have been identified, of which 24 are from abroad]. GOV.IL (in עברית). Retrieved 29 April 2021.
    163. ↑ "Indisk virusvariant påvist i Norge" [Indian virus variant detected in Norway]. dagbladet.no. 16 April 2021. Retrieved 28 April 2021.
    164. ↑ "Update On Covid-19 (08th May 2021) - SA Corona Virus Online Portal". SA Corona Virus Online Portal. Retrieved 10 May 2021.
    165. ↑ "Minister zdrowia: mamy kolejne dwa ogniska związane z mutacją indyjską koronawirusa" [Health Minister: We have two more outbreaks related to the Indian mutation of the coronavirus]. tvn24.pl (in polish). 4 May 2021. Retrieved 4 May 2021.{{cite web}}: CS1 maint: unrecognized language (link)
    166. ↑ "Lithuania detects first case of coronavirus Delta variant from India". lrt.lt/en/news-in-english. 17 June 2021. Retrieved 17 June 2021.
    167. 1 2 "Indian Covid variant reaches Finland". YLE. Finland. 29 April 2021. Retrieved 13 May 2021.
    168. ↑ "Intialaiseen muunnokseen on sairastunut Suomessa kymmenkunta henkeä – Uudenmaan koronaviruskanta on vaihtunut täysin alkuvuoden aikana" [About a dozen people in Finland have contracted the Indian variant - the coronavirus variants seen in Uusimaa have completely changed in the first part of the year]. yle.fi (in Finnish). 10 May 2021. Retrieved 17 May 2021.{{cite web}}: CS1 maint: unrecognized language (link)
    169. ↑ "Virologist: Indian variant not major concern in Finland, though care should be taken". Yle. Finland. 27 May 2021. Retrieved 27 May 2021.
    170. ↑ "Situation update on coronavirus - Coronavirus variants". Finnish Institute for Health and Welfare. 11 August 2021. Retrieved 11 August 2021. Delta-variant: 2,876
    171. ↑ de Vera, Analou (9 December 2021). "DOH: No Omicron variant yet in PH". Manila Bulletin. Retrieved 10 December 2021.
    172. ↑ "Philippines detects 492 new Omicron cases, total at 535". GMA News. 19 January 2022. Retrieved 24 January 2022.
    173. ↑ "Russia records first cases of COVID variant found in India". The Economic Times. Retrieved 13 May 2021.
    174. ↑ "Indian variant of Covid-19 confirmed in Thailand". Bangkok Post. 10 May 2021. Retrieved 11 May 2021.
    175. ↑ Osborne, Samuel (23 August 2021). "COVID-19: New Zealand extends coronavirus lockdown amid Delta variant outbreak". Sky News. Retrieved 23 August 2021. New Zealand reported 35 new cases of COVID-19, bringing the number of current infections to 107.
    176. ↑ Clark, Emily (22 August 2021). "New Zealand COVID-19 outbreak grows, strict lockdown extended". abc.net.au. Retrieved 23 August 2021. The strict level 4 lockdown across New Zealand has been extended as the country's Delta outbreak climbs to more than 100 cases.
    177. 1 2 3 "Nigeria, Algeria report Indian variant of the coronavirus, WHO says without further details". africanews.com. 13 May 2021. Retrieved 14 May 2021.
    178. ↑ "Covid Indian Variant Detected In Kenya". ndtv.com. 5 May 2021. Retrieved 7 May 2021.
    179. ↑ "Vietnam detects 'double mutant' Indian variant of coronavirus for 1st time". tuoitrenews.vn. 2 May 2021. Retrieved 17 May 2021.
    180. ↑ "Indian coronavirus variant found in COVID-19 cases linked to National Hospital for Tropical Diseases". vietnamnews.vn. 11 May 2021. Retrieved 17 May 2021.
    181. ↑ "IEDCR: Indian Covid variant found in six Bangladeshis". Dhaka Tribune. 17 May 2021. Retrieved 18 May 2021.
    182. ↑ "যশোরে আরো ৩জনের শরীরে করোনার ভারতীয় ভ্যারিয়েন্ট শনাক্ত" [Indian variant of coronavirus identified in 3 more people in Jessore District]. Youtube. Jamuna TV. 18 May 2021. Retrieved 18 May 2021.
    183. ↑ "Covid-19 Indian variant spreads to neighbouring countries; detected in Sri Lanka, Bangladesh". Times of India. 8 May 2021. Retrieved 11 May 2021.
    184. ↑ "Botswana confirms new COVID-19 variant". Weekend Post. 17 May 2021. Retrieved 18 May 2021.
    185. ↑ "Cases of South African and Indian coronavirus strains detected in Argentina". MercoPress. 11 May 2021. Retrieved 11 May 2021.
    186. ↑ "Raising fears of COVID surge, Uganda detects Indian variant, official says". Reuters. 30 April 2021. Retrieved 8 May 2021.
    187. ↑ "Nepal reports more Covid-19 deaths and record daily new infections". Kathmandu Post. 11 May 2021. Retrieved 11 May 2021.
    188. ↑ Yabiladi.com. "Morocco : Two cases of the Indian variant of Covid-19 confirmed in Casablanca". en.yabiladi.com (in français). Retrieved 3 May 2021.
    189. 1 2 3 4 "Weekly epidemiological update on COVID-19 - 18 May 2021". World Health Organization. 18 May 2021. Retrieved 19 May 2021.
    190. ↑ Lamb, Kate (10 August 2021). "East Timor detects first domestic transmission of COVID-19 Delta variant". Reuters. Retrieved 13 August 2021.|
    191. ↑ "Algeria finds first cases of Indian coronavirus variant". Reuters. 4 May 2021. Retrieved 14 May 2021.
    192. ↑ "Iran reports three cases of Indian coronavirus variant". Al Arabiya. 5 May 2021. Retrieved 14 May 2021.
    193. ↑ "Coronavirus: New Variants Confirmed in 15 New Cases". Hungary Today. 22 July 2021. Retrieved 28 August 2021. Tests by the National Public Health Centre (NNK) showed the presence of the Delta variant of the coronavirus in 14 new cases and the gamma variant in one new case, the prime minister's chief of staff said on Thursday.
    194. ↑ "Cyprus finds first cases of Indian COVID variant". Reuters. 19 May 2021. Retrieved 19 May 2021.
    195. ↑ "First case of Indian variant detected at Tocumen International". ndtv.com. 8 May 2021. Retrieved 14 May 2021.
    196. ↑ "PANGO lineages Lineage B.1.617". cov-lineages.org. Archived from the original on 3 June 2021. Retrieved 26 May 2021.
    197. ↑ SARS-CoV-2 variants of concern and variants under investigation in England - Technical briefing 10 (PDF) (Report). London. Public Health England. 7 May 2021. Archived (PDF) from the original on 8 May 2021. Retrieved 7 May 2021. This article contains OGL licensed text This article incorporates text published under the British Open Government Licence v3.0:
    198. ↑ "British scientists warn over Indian coronavirus variant". Reuters. 7 May 2021. Archived from the original on 22 May 2021. Retrieved 7 May 2021.
    199. ↑ Davis, Nicola (7 May 2021). "Indian Covid variant is 'of concern', says Public Health England". The Guardian. London. Archived from the original on 7 May 2021. Retrieved 7 May 2021.
    200. ↑ "Confirmed cases of COVID-19 variants identified in UK". www.gov.uk. 3 June 2021. Archived from the original on 7 May 2021. Retrieved 3 June 2021. This article contains OGL licensed text This article incorporates text published under the British Open Government Licence v3.0:
    201. ↑ "Confirmed cases of COVID-19 variants identified in UK". www.gov.uk. 11 June 2021. Archived from the original on 11 June 2021. Retrieved 11 June 2021. This article contains OGL licensed text This article incorporates text published under the British Open Government Licence v3.0:
    202. ↑ Carrigg, David (21 April 2021). "COVID-19: Double mutant virus first identified in India is now in B.C." Vancouver Sun. Archived from the original on 22 April 2021. Retrieved 28 April 2021.
    203. ↑ Ritchie, Josh (22 April 2021). "First case of B.1.617 variant confirmed in Alberta". edmonton.citynews.ca. Archived from the original on 23 April 2021. Retrieved 10 April 2023.
    204. ↑ "One Death, Eight New Cases of COVID-19, Delta Variant Cases Identified, State of Emergency Renewed". 11 June 2021. Archived from the original on 12 June 2021. Retrieved 11 June 2021.
    205. ↑ "Fiji fears a coronavirus 'tsunami' after outbreak found to be Indian variant". SBS News. 28 April 2021. Archived from the original on 27 April 2021. Retrieved 28 April 2021.
    206. ↑ "Philippines detects 2 cases of COVID-19 India variant". Rappler. 11 May 2021. Archived from the original on 11 May 2021. Retrieved 11 May 2021.
    207. ↑ "Индиската варијанта на ковид-19 се заканува од есен да направи хаос" [The Indian variant of covid-19 threatens to wreak havoc in the autumn]. Sloboden Pecat (in македонски). Skopje. 22 June 2021. Archived from the original on 9 July 2021. Retrieved 30 June 2021.
    208. 1 2 Shakil, F.M. (18 May 2021). "Pakistan in blind denial over Indian virus variant". Asia Times. Archived from the original on 18 May 2021. Retrieved 19 May 2021.
    209. ↑ "Iraqi labs don't have ability to identify Indian Covid variant". Healthworld, Economic Times. 11 May 2021. Archived from the original on 19 May 2021. Retrieved 19 May 2021.
    210. ↑ "ECDC warns Delta variant to become 90% prevalent in EU by end-August". Reuters. 23 June 2021. Archived from the original on 4 July 2021. Retrieved 15 April 2022.
    211. ↑ Roy, Mrinalika (7 July 2021). "Delta variant already dominant in U.S., CDC estimates show". Reuters. Archived from the original on 15 March 2022. Retrieved 15 April 2022.
    212. 1 2 Public Health England (9 July 2021). "Variants of Concern Technical Briefing 18" (PDF). UK Government. Archived (PDF) from the original on 10 July 2021. Retrieved 13 July 2021.
    213. ↑ Public Health England (18 June 2021). "Variants of Concern Technical Briefing 16" (PDF). UK Government. Archived (PDF) from the original on 30 June 2021. Retrieved 13 July 2021.
    214. ↑ "SARS-CoV-2 variants of concern and variants under investigation in England" (PDF). assets.publishing.service.gov.uk. Public Health England Technical Briefing 15. 11 June 2021. p. 22. Archived (PDF) from the original on 4 July 2021. Retrieved 4 July 2021.This article contains OGL licensed text This article incorporates text published under the British Open Government Licence v3.0:
    215. ↑ Wise, Jacqui (21 May 2021). "Covid-19: UK cases of variant from India rise by 160% in a week". BMJ. 373: n1315. doi:10.1136/bmj.n1315. ISSN 1756-1833. PMID 34020965. S2CID 235075923. Archived from the original on 9 July 2021. Retrieved 10 April 2023.
    216. ↑ report, Web. "India Covid crisis: 20 countries that have imposed travel bans, suspensions". Khaleej Times. Archived from the original on 1 May 2021. Retrieved 1 May 2021.
    217. ↑ "Countries enact travel bans to contain India's COVID variant—and protect against 'a global resurgence all over again'". Fortune. Archived from the original on 1 May 2021. Retrieved 1 May 2021.
    218. ↑ "Countries that have put India in red list due to rising COVID-19 cases". The Times of India. Archived from the original on 1 May 2021. Retrieved 1 May 2021.
    219. ↑ "Indian variant: Tower blocks quarantined in Germany". BBC News. Archived from the original on 19 May 2021. Retrieved 19 May 2021.
    220. ↑ "'Freedom Day' for England pushed back 4 weeks to July 19". AP News. 14 June 2021. Archived from the original on 15 June 2021. Retrieved 15 June 2021.
    221. ↑ "How Dangerous Is the Delta Variant, and Will It Cause a COVID Surge in the U.S.?". Scientific American. 29 June 2021. Archived from the original on 29 October 2021. Retrieved 10 April 2023. cited Scientific Pandemic Influenza Group on Modelling, Operational sub-group (SPI-M-O) (2 June 2021). "SPI-M-O: Consensus Statement on COVID-19" (PDF). SAGE, UK Government. Archived (PDF) from the original on 20 July 2021. Retrieved 10 April 2023.{{cite web}}: CS1 maint: uses authors parameter (link)
    222. ↑ "Ontario Covid-19 Vaccine Update June". Toronto Citynews. Archived from the original on 17 June 2021. Retrieved 13 July 2021.
    223. ↑ "Israel requires masks indoors again as Delta variant drives up cases". Reuters. 25 June 2021. Archived from the original on 8 July 2021. Retrieved 13 July 2021.
    224. ↑ "Australia Locks Down to Fight Coast-to-coast Covid-19 Outbreaks". NPR. 28 June 2021. Archived from the original on 11 July 2021. Retrieved 13 July 2021.
    225. ↑ Cyril Ramaphosa. "President Cyril Ramaphosa: South Africa's response to Coronavirus COVID-19 pandemic | South African Government". Government of South Africa. Archived from the original on 14 August 2021. Retrieved 13 July 2021.
    226. ↑ Jessie Yeung (5 July 2021). "Dozens die in Indonesia hospital with oxygen shortage, as Delta variant sweeps the country". CNN. Archived from the original on 15 December 2021. Retrieved 13 July 2021.
    227. ↑ "Olympics host city Tokyo bans spectators amid COVID-19 emergency". Reuters. 8 July 2021. Archived from the original on 12 July 2021. Retrieved 13 July 2021.
    228. ↑ "South Korea reverses loosening of mask mandate, ramps up curbs as cases soar". Washington Post. Archived from the original on 13 July 2021. Retrieved 13 July 2021.
    229. ↑ "Mandatory vaccination, Covid-19 pass and access to PCR tests: the main points from Macron's address". France24. 12 July 2021. Archived from the original on 15 December 2021. Retrieved 13 July 2021.
    230. ↑ McCarthy, Lauren (15 July 2021). "Los Angeles County will require masks to be worn indoors as Delta variant spreads". New York Times. Archived from the original on 16 December 2021. Retrieved 16 July 2021.
    231. ↑ "'We are a petri dish': world watches UK's race between vaccine and virus". the Guardian. 2 July 2021. Archived from the original on 8 July 2021. Retrieved 25 July 2021.
    232. ↑ "COVID-19: Sajid Javid's approach has party support - but scientists are getting worried". Sky News. Archived from the original on 9 July 2021. Retrieved 25 July 2021.
    233. ↑ "Vietnam locks down capital Hanoi as COVID-19 infections soar". www.aljazeera.com. Archived from the original on 14 November 2021. Retrieved 25 July 2021.
    234. ↑ "Vietnam's biggest cities tighten restrictions as COVID-19 cases surge". Reuters. 23 July 2021. Archived from the original on 3 December 2021. Retrieved 25 July 2021.
    235. ↑ "New Zealand enters nationwide lockdown over one Covid case". BBC News. 17 August 2021. Archived from the original on 5 November 2021. Retrieved 18 August 2021.
    236. ↑ "New Zealand reports first Covid-19 case in community since February". The Guardian. 17 August 2021. Archived from the original on 23 October 2021. Retrieved 18 August 2021.
    237. ↑ "COVID-19: 'Delta is making other coronavirus variants extinct' - but what does it mean for the UK?". Sky News. Archived from the original on 17 August 2022. Retrieved 17 August 2022.
    238. ↑ Rachael Rettner (23 March 2022). "Coronavirus variants: Facts about omicron, delta and other COVID-19 mutants". livescience.com. Archived from the original on 17 August 2022. Retrieved 17 August 2022.
    This article is issued from Offline. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.