COVID-19 vaccination in Bulgaria

Bulgaria eventually agreed to purchase all seven vaccines included in the European portfolio - Moderna, Pfizer-BioNTech, Oxford–AstraZeneca, Sanofi, CureVac, Novavax, and Janssen,[67] even though it had some reservations regarding its participation in the contract with Janssen Pharmaceutica.[68] On 14 October 2020 Bulgaria explicitly refused to pre-order the latter's vaccine candidate as part of the EU-wide deal,[69] but reversed course in November and ratified a separate agreement for 2 million doses in December, aided by Sweden's cooperation,[69] with the change of heart partly attributed to concerns pertaining to the progress made by Oxford-AstraZeneca at the time.[69] Some Bulgarian experts reportedly considered the European vaccine portfolio to be overly diverse.[69][70] After major delays due to trial issues of Sanofi and GlaxoSmithKline's vaccine candidate, for 2021 the country was in the initial months mostly reliant on the Oxford–AstraZeneca COVID-19 vaccine, expecting to receive enough doses for vaccinating 2.5 million citizens.[71] After at first ordering 1 million doses from Pfizer-BioNTech, on 13 January 2021 when the European Commission announced that it had concluded an agreement for extra 300 million doses with this vaccine producer, Bulgaria requested additional 2.9 million Pfizer-BioNTech vaccines,[72] with a later agreement resulting in the quantity of pre-ordered doses of this vaccine for 2021 rising to 5.4 million.[73]

In total, the amount of vaccine pre-ordered or set to be ordered by the country is expected to be equivalent to 18 million doses, able to cover 9 million citizens.[74][75]

In May 2021, Bulgaria made a pre-order for 14 million Pfizer vaccine doses for 2022 and 2023.[76]

In August 2021, it was revealed that Bulgaria had pre-ordered a new type of attenuated vaccine, developed by Valneva Austria.[77] In September 2021, it was confirmed that Bulgaria will buy only 10,000 out of the pre-arranged doses from the one-shot Sanofi Pasteur SA/Glaxosmithkline Biologicals SA vaccine, which are to be delivered in 2022.[78]

On 25 February 2021, Angelov publicly reproached AstraZeneca after it became clear that the pharmaceutical company will be able to provide 40% of the promised vaccines by August. Bulgaria had also offered to assist with the delivery of the next batch of vaccines by sending its own airplane, but this suggestion had not been accepted.[79] On the next day it was revealed that there is an alternative plan, which will entail receiving an extra 1 million Pfizer-BioNtech and 480 000 Moderna doses between March and June.[80]

On 28 February 2021, Boyko Borisov confirmed that Bulgaria had entered talks to borrow vaccines from EU countries where there is no queuing for them, so that Bulgaria does not have to halt its vaccination process.[81][82] On 1 March 2021, it was disclosed that Bulgaria had arranged for over 450 000 additional doses of the Moderna vaccine, as a result of a direct agreement with Sweden.[83]

In early March 2021, Bulgaria and five other EU countries (Slovenia, Croatia, Austria, Czech Republic, and Latvia) insisted that a new debate is initiated regarding the allocation of the vaccines within the EU bloc, with Boyko Borisov echoing Austrian Chancellor Sebastian Kurz's sentiment[84][85] that some EU states had received more vaccines than warranted by their population numbers.[86] On 13 March 2021, the European Commission sent out statement clarifying that some member states, with Bulgaria being implied to be among them,[87] had on their own accord deviated from the principle of pro rata allocation during the initial placing of orders for vaccines, freeing up additional doses for other countries.[88] Bulgaria is believed to have refrained from exercising its option of ordering 30 million doses in total.[89] On 26 March 2021, Croatian Prime Minister Andrej Plenković stated that Bulgaria should receive the most relative to the other countries out of the 10 million doses of Pfizer-BioNTech vaccines that will arrive in the second quarter of the year, earlier than scheduled, as a compensation for the production issues faced by AstraZeneca.[90] Even though Austria (that led the redistribution campaign), Slovenia and the Czech Republic rejected the eventual proposal that was arrived at,[91] in early April 2021, it was confirmed that Bulgaria (alongside Croatia, Slovakia, Latvia, and Estonia) will in addition to getting its pro rata allocation, also benefit from the sharing of 2.85 million "solidarity vaccines" (out of the 10 million doses) among these five countries.[92][93]

In May 2022, the Ministry of Health sent out a letter to the European Commission, emphasizing that while it remains committed to securing a wide range of vaccines for Bulgarian citizens, it believes that there should be a high degree of flexibility regarding the amount of vaccines bought, in accordance with the needs of the population in order not to have another scenario with an excess of vaccines.[94]

According to Todor Kantardzhiev, one of the members of the National Operational Headquarters for the fight against the coronavirus, Bulgaria has not ruled out the purchase of vaccines from companies with which the European Commission has not negotiated contracts, such as Sputnik and the Sinopharm BIBP vaccine, as long as EU regulations are observed[95] and especially if there is a delay regarding the delivery of the other vaccines.[96]

On 26 February 2021, the opposition BSP party demanded that the government begin separate talks with Russia for the importation of the Sputnik vaccine.[97] The Health Commission of the National Parliament initially rejected the proposal, but on 28 April 2021 accepted BSP's demands.[98] However, even though ITN, Stand Up! Mafia, Get Out! and one deputy from Democratic Bulgaria joined forces with BSP during the vote on 7 May 2021,[99] the proposal still did not pass the required threshold in the National Parliament, which would have empowered the Council of Ministers to take all necessary measures to secure access to Sputnik.[100] Ethnic Bulgarians have been administered the Sputnik vaccine in Russia.[101]

Microbiologist Andrey Chorbanov has pointed out that the country already imports medications that are not regulated by the EU, so the thinking should not be different when it comes to the Russian vaccine.[102] The importing of vaccines from third countries was also supported by the RzB party, even if the EU is bypassed and only the Bulgarian Drug Agency approved them.[103] Some journalists noted that Bulgaria recognized the vaccinations of foreign citizens with Sputnik as well as with the Sinopharm BIBP vaccine and CoronaVac as one of the conditions for entry into the country.[104]

A COVID-19 vaccine based on nanoparticles is presently under development by the BAS,[105][106] with completed preclinical research, but despite receiving financial support from the Pasteur Institute, issues related to funding are expected to significantly slow down the progress when it comes to the vaccine trials.[107] It was unveiled to the wider public at the 15th World Congress of Vaccines held online in October 2021.[108][109]

The National Center of Infectious and Parasitic Diseases in Sofia where some of the COVID-19 vaccines have been stored prior to their distribution.

Kostadin Angelov, the former Minister of Health, has on a number of occasions reiterated that Bulgarians should be able to have a choice regarding the type of vaccine they are to receive.[110][111]

Four vaccines are currently available for use in Bulgaria.

The first to be administered in the country was Pfizer–BioNTech, which was approved by the European Commission on 21 December 2020, on the same day after receiving recommendation for granting conditional marketing authorization by the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA),[112] with the initial doses delivered to Bulgaria 26 December,[113] arriving from Belgium.[114]

On 6 January 2021, following the same regulatory procedure, the Moderna vaccine was also given the green light by the European Commission,[115] arriving in Bulgaria a week later.[116]

On 29 January 2021, Oxford–AstraZeneca vaccine received conditional authorization by the European Commission, paving the way for its use in EU countries.[117] On the same date, Kostadin Angelov stated in an interview with Boyko Vasilev during the TV show Panorama that Bulgaria will wait for the results of further studies regarding its effectiveness when it comes to people over the age of 65 before administering it to members of this age group.[111] On 4 February 2021, Angelov clarified that there is no medical prohibition to give the vaccine to elderly people and that an additional statement will be made before Oxford-AstraZeneca begins to be administered.[118] The government eventually concluded that the vaccine is useful for elderly citizens as well and did not exclude them from receiving it.[119][120] The first batch of this vaccine reached Bulgaria on 6 February 2021.[121]

On 11 March 2021, the one-shot Janssen vaccine (Johnson & Johnson) became the fourth vaccine to be conditionally approved on the EU level,[122] arriving in Bulgaria slightly over a month later.[123]

On 28 May 2021, EMA approved the administering of the Pfizer–BioNTech vaccine to children in the age range from 12 to 15.[124]

On 23 July 2021, the same agency gave the green light for the use of the Moderna vaccine in children aged from 12 to 17.[125]

On 4 October 2021, EMA recommended an extra dose, using either Pfizer–BioNTech or Moderna, for people aged 12 or above whose immune system is severely weakened, to be administered at least 28 days after the second injection.[126] It also stated that such a booster dose may be considered, with Pfizer–BioNTech, for all other people aged 18 or over at least six months after the second shot.[127] On 25 October 2021, the same agency also approved the administering of a booster dose with Moderna for all adults.[128]

In November 2021, the Ministry of Health revealed that no deliveries of AstraZeneca had been made to Bulgaria since August 2021.[76] Only 491 doses of this vaccine had been administered in September 2021 compared to over 60 000 in June 2021.[129] However, in January 2022, 4800 new doses of AstraZeneca arrived in Bulgaria in response to specific demand for this vaccine.[130]

On 25 November 2021, the Pfizer–BioNTech became the first COVID-19 vaccine in the EU to be approved for children below the age of 12,[131] with the first pediatric doses arriving in Bulgaria on 20 December 2021.[132][133]

On 15 December 2021, EMA approved the use of the Janssen vaccine as a booster.[134] On 10 January 2022, Bulgaria followed suit in giving the nod to such an application of this vaccine. It can be administered two months after full vaccination (one dose) with the same vaccine and three months after a two-dose vaccination regimen with Pfizer–BioNTech or Moderna.[135]

On 20 December 2021, Novavax joined the list of vaccines that can be used in the EU after receiving approval from EMA.[136] Bulgarian health authorities confirmed that the country is yet to order doses from Novavax due to the country having an excess of vaccines.[137] In January 2022, Health Minister Assena Serbezova stated that Bulgaria is looking at the option of obtaining Novavax vaccine doses from Sweden.[138]

On 24 February 2022, Moderna was endorsed by EMA regarding its use in children aged from 6 to 11 years old[139] and on 2 March 2022 the European Commission followed suit in approving the vaccine for children in this age cohort.[140] Bulgarian health authorities gave it the green light for use in children in this age group from 11 March 2022.[141]

Vaccine	Doses ordered[142][lower-alpha 3][lower-alpha 4]	Approval	Deployment
Pfizer–BioNTech	5.4 million	21 December 2020	27 December 2020[lower-alpha 5][lower-alpha 6]
Moderna	0.96 million	6 January 2021	14 January 2021[lower-alpha 7][lower-alpha 8]
Oxford-AstraZeneca	4.5 million	29 January 2021	7 February 2021[lower-alpha 9]
Janssen	2 million	11 March 2021	28 April 2021[145][lower-alpha 10]
Novavax[lower-alpha 11]	1.55 million	20 December 2021	Pending
CureVac	1 million	Pending	Pending
Sanofi	4.65 million	Pending	Pending

The Sofia Regional Health Inspectorate, which has held a coordinating role regarding the vaccination campaign.

Towards the end of May 2021, Bulgaria confirmed that 50,000 AstraZeneca Oxford-AstraZeneca doses will be given to North Macedonia.[147] With the supply of vaccines outstripping demand during the summer months, in July 2021 Bulgaria donated 172,500 doses of its AstraZeneca vaccines that were close to their expiration date to Bhutan.[148] In August 2021, 50,000 doses of the same vaccine were given to Bosnia and Herzegovina as a donation[149] while an agreement was reached with North Macedonia for the provision of 51,480 doses of the Pfizer–BioNTech vaccines as well as with Bhutan for another 172,500 AstraZeneca shots.[150] During the same month, approximately 100,000 Moderna doses were resold to Norway[151][152] and the country was also in the process of reselling 546,000 Pfizer-BioNTech vaccines to Portugal.[73] In September 2021, it was also confirmed that Bangladesh will be the recipient of around 270,000 AstraZeneca doses.[153][154] The country subsequently donated 258,570 Pfizer-BioNTech doses to Bosnia and Herzegovina as well as 2,830,400 AstraZeneca vaccines to Iran.[155]

As of October 2021, 184,089 AstraZeneca, 12,955 Moderna, 4500 Pfizer and 199 Janssen vaccine doses had been discarded due to reaching their expiration dates and no option for using them.[76] The country has also been experiencing issues due to the limited amount of incinerators for disposing of unusable doses.[156] As of August 2022, due to the low vaccine uptake, over 1,3 million vaccine doses had been declared unusable, with 1,6 million expected to have the same fate by the end of the year.[157]

Asparouh Iliev, a Bulgarian specialist in molecular neuroinfectiology from the University of Bern, has praised the two RNA vaccines, characterizing them as extremely safe and also regarding them as very similar to each other.[320] He has pointed out that the AstraZeneca vaccine has an excellent safety profile[321] and may actually be offering even better protection than shown from the preliminary studies, considering the whole comparison exercise between the three vaccines to be pointless, urging people to take up the opportunity to get themselves vaccinated,[322] with allergist Bogdan Petrunov maintaining that AstraZeneca is in no way inferior to the RNA vaccines.[323]

In April 2021, pulmonologist Kosta Kostov, while acknowledging the issue of vaccine reservations in Bulgaria, also stated that the narrative that all approved vaccines on the EU level are equally safe and effective is fallacious.[23]

An influenza vaccine to be used in Bulgaria during the autumn and winter of 2022.

Andrey Chorbanov, a member of the Institute of Microbiology at BAS and a leading figure behind the ongoing development of the Bulgarian vaccine,[324] while supportive of vaccinating vulnerable groups, maintains that naturally acquired immunity is much stronger than the vaccine-induced one, believing that the people who have recovered from COVID-19 have very durable immunity[102] and has opposed mandatory vaccinations against COVID-19 for young and healthy people.[325] In his view, the major question mark surrounding the vaccines remains their actual effectiveness while their safety and the side effects are not an issue.[102] Similarly, immunologist Velizar Shivarov affirms that people who have antibodies can afford to wait to be vaccinated.[326] In February 2021, Todor Kantardzhiev, a member of the National Operational Headquarters for the fight against the coronavirus in Bulgaria, claimed that one vaccine dose may be sufficient for the people who have recovered from a COVID-19 infection[327] and has also expressed the viewpoint that a person who gets infected between the two jabs may not need the second injection.[328] Allergist Bogdan Petrunov and neuroinfectiologist Asparouh Iliev[329] have contested Chorbanov's claims, emphasizing that vaccine-induced immunity is significantly more reliable than the naturally acquired one, especially with regard to the mutant strains of the virus,[323] thus offering a greater breadth of protection, even if infection-generated immunity can be quite strong.[330]

People who have recovered from COVID-19 may undergo the two-dose vaccination process no earlier than 3 months after the laboratory confirmation of their diagnosis.[331]

In the case of citizens who become infected after receiving their first injection (in the case of two-shot vaccines), the second dose of the vaccine is to be administered at least 6 months after the laboratory diagnosis has become official.[331]

The recommendations of the National Vaccination Operational Headquarters in Bulgaria are that the second dose of the Oxford-AstraZeneca vaccine be administered at least 10 weeks after the first.[332]

The mixing of different types of vaccines, especially when it comes to attempting to complete the second step of the vaccination process by using another vaccine, was initially not advised,[333] but was still considered a possibility, depending on the conclusions of further studies[327] and there are currently indications that combining AstraZeneca and Pfizer may generate a more powerful immune response,[334] as adenovirus vaccines tend to be superior in stimulating T cell responses while RNA ones produce higher antibody levels.[335] Virologist Radostina Aleksandrova notes that the protective antibody titers as a result of the mixing of these vaccines can be up to six times higher, though cautions that the sample sizes in terms of study participants have been small and there are some uncertainties regarding the efficacy and safety.[335]

In April 2021 the Health Minister clarified that Oxford-AstraZeneca will not be administered to women under the age of 60 with an elevated risk for thrombosis and/or a history of thrombocytopenia.[331] Chief Health Inspector Angel Kunchev stated that women under 30 who are heavy smokers, take contraceptives and are overweight are the most at risk for blood clots.[336] The people who have received the first dose of this vaccine without experiencing any serious adverse effects may complete the vaccination process with the same one while those who do not wish so may choose one of the two RNA vaccines for their second jab, but no earlier than 84 days after the first Oxford-AstraZeneca injection.[331] Bulgaria had previously also considered combining the AstraZeneca and Johnson & Johnson vaccines.[249] As of 10 May 2021, it was reported that very few of the people who were due their second dose had decided to pick a RNA vaccine instead of AstraZeneca.[168][255] On 26 August 2021, it was revealed that approximately 3000 Bulgarians had opted to take a RNA vaccine as their second dose.[151]

Immunologist Bogdan Petrunov has recommended that Bulgarians also get the flu vaccine in addition to a COVID-19 one.[337] In Bulgaria a number of medical practitioners advise that there is at least a ten-day[338] to a two-week interval between the administering of a flu and a COVID-19 vaccine.[339] However, both shots can also be received simultaneously, according to autumn 2022 guidelines from the Ministry of Health,[340] which are consistent with the advice of the European Commission and the WHO.[341] The country bought 190,000 influenza vaccines for the period between October 2022 and February 2023.[340]

An outdoor table at a café in Krasno selo requiring a green certificate.

An eating establishment with a presumably fully vaccinated staff.

According to experts, there is no need for a person who is asymptomatic or mildly symptomatic to be tested for COVID-19 prior to getting the vaccine.[342][343] A person who has been vaccinated is generally recommended to be kept for observation for 15–20 minutes in the rare case any potential side effects need to be managed.[16][344] People who want to receive a booster dose do not need to be tested for antibodies.[275] In October 2021, the Ministry of Health published further information regarding the contraindications to an immunization with Pfizer-BioNTech - having a severe allergy to a component of the vaccine, belonging to an age group below that specified in the short characteristics of the vaccine and being in isolation or showing symptoms of COVID-19.[345] Due to the low vaccination rate, caretaker health minister Asen Medzhidiev stated in August 2022 that medical practitioners will be allowed to open multiple dose vials of the Pfizer-BioNTech vaccine even if there is only one person present who is wishing to be vaccinated.[157]

As of 4 January 2021, only 4 adverse reactions to the vaccines administered had been reported to the Executive Agency for Medicines - they included headaches and muscle pain, with all of the recipients' symptoms quickly subsiding.[214] As of 12 March 2021, slightly over 830 messages regarding unwelcome side effects had been filed.[346] As of 19 March 2021, about 1200 such reports had been submitted, with the frequency being 4 for every 1000 vaccinated for AstraZeneca, 3 for every 1000 individuals for Moderna, and slightly over 2 per 1000 for Pfizer.[347] According to other sources, the frequency of such complaints for all three vaccines was roughly 3.2 for every 1000 shots administered, with high fever (over 38 degrees Celsius) seen as a more typical side effect of AstraZeneca.[348] As of 17 January 2022, 3861 complaints had been posted, with 10% of them assessed to meet the seriousness criteria, and no fatal outcomes conclusively proven to have been linked to vaccines.[349] The latter clarification was made largely in response to allegations made by controversial infectiologist Atanas Mangarov who had made statements suggesting that there had been fatalities attributable to the vaccines.[350] As of 3 May 2022, 4069 such messages had been submitted, equivalent to a frequency of 0.92 post-vaccination effects per 1000 doses.[351] As of 1 September 2022, 4176 such notifications had been received, equaling the same ratio of 0.92 vaccine-related grievances per 1000 doses.[300]

Bogdan Kirilov, the executive director of the Bulgarian Drug Agency, noted that all of the serious adverse reactions in the case of AstraZeneca had occurred after the first dose.[352] According to a Ministry of Health report from October 2021, side effects are more frequent after the second dose in the case of RNA vaccines, with high fever being rare.[353] Todor Kantardzhiev stated in January 2021 that the side effects of the COVID-19 vaccines are no different from those of the influenza vaccines.[354]

In March 2021, a number of EU countries temporarily suspended vaccinations with Oxford AstraZeneca after reports of fatal or life-threatening blood clots with low platelet counts in a few people who had recently received a dose, even though no direct causal link has been established with the vaccine.[355] Bulgaria is among the 17 EU recipients of vaccines that are part of the ABV5300 batch,[356] which has been under investigation by the Austrian health authorities as well as by the European Medicines Agency (EMA).[357] Bulgaria had received 31 200 doses from this batch on 12 February, with most of them administered, but no serious adverse effects were reported until 12 March.[357] Bogdan Kirilov, the executive director of the Bulgarian Drug Agency, initially stated that the country intended to continue the vaccination process as planned.[357] However, on 12 March 2021, Boyko Borisov ordered that vaccinations with AstraZeneca be halted until a written opinion is provided by EMA, clearing all doubts regarding the vaccine's safety.[358][359] As a result, Kirilov mandated that all of the AstraZeneca doses in the country are temporarily blocked from distribution and use.[360] The decision had also been influenced by the reported fatality of a 57-year-old woman from Plovdiv with multiple comorbidities shortly after vaccination.[241] On 18 March 2021, EMA released a statement that it still considers the benefit-risk balance of the vaccine to be positive.[361] It was also determined that no thrombosis had been observed in the case of the 57-year-old Bulgarian citizen.[362] AstraZeneca vaccinations recommenced in Bulgaria on the next day.[242] On 21 May 2021, EMA introduced a contraindication for a second shot of AstraZeneca in the case of blood clots with low blood platelets (thrombosis with thrombocytopenia syndrome) occurring after the first injection[363] and on 11 June 2021 issued a warning against the administering of this vaccine to people with capillary leak syndrome.[364]

After a similar issue halted the distribution of Johnson & Johnson, on 20 April 2021, EMA confirmed that it had discovered a link between the vaccine and instances of very rarely occurring unusual blood clots with low blood platelets, stating that the product information should contain such a warning while also assessing the benefit-risk balance to be in favour of the vaccine.[365]

From 25 May 2022, the time interval for children aged 12 to 17 in which they can receive a Pfizer-BioNTech booster dose after completing their regular vaccination regimen with the same vaccine was shortened from six to three months.[366]

Leading immunological laboratories in the country will be monitoring at least 1000 Bulgarians for a period of two years in order to assess the nature and durability of their immunity to COVID-19.[367]

A screenshot from the electronic registration system after vaccinations with Oxford-AstraZeneca were temporarily put to a halt.

The officially registered COVID-19 cases in Bulgaria are believed to underreport the actual number of infections by a factor of at least 2,[7][392] mathematician Lachezar Tomov surmising that the underestimation is sixfold,[393] with a significant amount of hidden COVID-19 afflictions consistently eluding detection,[394] in part due to people buying COVID-19 test kits from pharmacies and not reporting to health authorities.[395] In the autumn of 2020, mathematicians such as Nikolay Vitanov multiplied the officially registered cases by 8 while since 2021 they have been multiplying them by 4 in order to get a clearer picture regarding the real epidemiological situation.[396][397] In the summer of 2022, mathematician Ognyan Kunchev estimated that the real number of cases may be potentially up to 10 times higher than the officially registered ones due to the low levels of testing and the transmissibility of Omicron.[398]

An epidemiological study from June 2020 reached the conclusion that 2% of Bulgarians had developed antibodies against COVID-19.[399] The Cibalab private laboratory analyzed 2665 samples collected throughout the country between 25 May and 11 June 2021, with 1158 from them (43%) showing a positive result for the presence of antibodies. This survey has been characterized as falling far short of standards for representativeness and as methodologically suspect, with the Health Ministry criticized by experts for publicizing the results.[400]

Alpha Research sociologists speculated, based on the results of a survey for the period between 11 and 18 December 2020, that 670,000 Bulgarians may have had the virus and recovered from it.[401] In February 2021, a Gallup survey conducted between the 4th and the 12th of that month drew the conclusion that 1.5 million Bulgarians may have had the virus.[402] In an April 2021 Gallup survey, close to one third of adult Bulgarians claimed to have either recovered from the virus or been vaccinated with two doses.[403]

Мathematician Nikolay Vitanov estimated in late January 2021 that some 20% of Bulgarians may have encountered the virus in some form.[404] In March 2021, physician Emil Hristov, drawing on various sources, provided an even higher estimate of between 2 and 2.5 million while also expressing skepticism that the number of vaccinated will start to exceed those who have recovered from infection any time soon.[405] Mathematician Lachezar Tomov claimed in March 2021 that any numbers in the vicinity of 2 million are most likely an overestimate,[7] though he stated that they were reached six months later - by September 2021.[29]

In late April 2021, Vitanov estimated a "shield" (recovered and vaccinated) of 33.6% Bulgarians against the virus.[406] In September 2021, taking into account the likelihood of reinfections, Lachezar Tomov assessed the "shield" to be around 40%.[29]

According to Nedyalko Kalachev, the head of the Cibalab laboratories, 12 024 out of 26 425 (45%) of the people who submitted samples for the month of November 2021 had IgG antibody levels above 150 BAU/ml (required for a green certificate unless the person has been vaccinated or has a negative test result), though he considers the truly protective threshold to be above 700 BAU/ml.[407]

Bulgaria will receive methodology from the EU for assessing the situation in the country in terms of natural and vaccine-generated immunity to the virus.[408]

According to Health Inspector Angel Kunchev 93.8% of the new COVID-19 infections during the third week of August 2021 were among non-vaccinated people.[409][410] Kunchev later announced that between 22 and 28 August 2021, 97% of COVID-19 fatal outcomes involved non-vaccinated Bulgarians.[411] Data provided by the Ministry of Health for the period between 1 March and 14 September 2021 indicated that 99.33% of the COVID-19 related fatalities in the country were among people who had not been vaccinated.[412] In the autumn of 2021, Ventsislav Mutafchiyski stated that over 90% of the COVID-19 patients in the Military Medical Academy were not vaccinated,[413] with over 98% of the cases with a lethal outcome being of non-vaccinated people.[414]

According to experts, taking into account the situation in early 2021, 60% vaccinated people plus those who have had the disease and recovered from it may be sufficient for herd immunity to kick in.[415] Then Health Minister Kostadin Angelov stated in February 2021 that at least 70% will need to be vaccinated in order to guarantee the return of normal life.[416] In May 2021, virologist Radostina Aleksandrova, taking into account the different mutations and the delay in vaccinations, tentatively calculated the herd immunity threshold to be at 80%[417] while in March mathematician Lachezar Tomov put the number at 85%, assuming the Alpha variant would become dominant in the country.[7] In July 2021, molecular biologist Georgi Marinov stated that herd immunity could be achieved if 90% of the people are immunized, though he also characterized it as likely a temporary state of affairs due to the waning immunity from the vaccines. He thus advised the Bulgarians immunized in December 2020 and January 2021 to already consider a second vaccination cycle.[418]

Asen Baltov, the director of Pirogov Hospital, cautioned in March 2021 that at least 3 million people will have to be vaccinated by August–September if the country is to avoid a fourth wave in the autumn of 2021,[419] with caretaker Health Minister Stoycho Katsarov also acknowledging in June 2021 that Bulgaria is facing a real risk of such a scenario occurring in case of insufficient vaccination rate and due to remaining issues in the health system.[420] Mathematician Lachezar Tomov stated in mid June 2021 that at least 30,000 new people will need to be vaccinated per day (until 15 September 2021) in order for the country to prevent this eventuality.[56]

In late April 2021, physician Nikolay Branzalov, taking into account the ratio of vaccinated and recovered to the newly infected, predicted that unless there are major virus mutations, escaping the vaccines, there will not be a next COVID-19 wave in Bulgaria.[421]

Ognyan Kunchev, a member of the Informatics and Mathematics Institute of BAS, estimated in March 2021 that the pandemic will peter out by the end of 2021 if 100,000-120,000 people are vaccinated per month, viewing it as likely that approximately 1 million Bulgarians have already had the virus.[422] Allergist Bogdan Petrunov stated in March 2021 that vaccinating 2 million Bulgarians may be sufficient for attaining herd immunity[323] while mathematician Lachezar Tomov has insisted that approximately 5 million vaccinated will be needed for collective immunity of the population.[423]

In mid April 2021, Kostadin Angelov stated that in an optimistic scenario herd immunity could be attained by the end of June, with the more realistic estimate being the end of July and the most pessimistic one considered to be the end of August.[424]

The different COVID-19 variants and their interactions with natural and vaccine-induced immunity are likely to change initial calculations when it comes to the herd immunity thresholds.

In June 2021, the presence of the Beta and Delta variants was detected by the National Center for Infectious and Parasitic Diseases in the country.[425][426] The latter established itself as the dominant variant (being found in over 50% of genomic sequencing samples) as early as mid July 2021, beginning to rapidly displace Alpha.[427] Delta's contagiousness and the still low vaccination coverage caused some experts to speculate that another wave may occur in Bulgaria by late August,[428] which eventually materialized as a scenario at that time.[429]

In September 2021, mathematician Lachezar Tomov stated that the wave driven by the Alpha variant that had affected Bulgaria during the spring could in part compensate for the very low level of vaccination coverage of the population, though he still expected a major rise in cases due to the beginning of the school year and the aggressiveness of the Delta variant, also expressing serious concern due to the lax pandemic control measures.[430]

In late November 2021, mathematician Antony Rangachev stated that the introduction of the green certificates and the switch to online education for some of the students had been the major factors contributing to the turning of the tide during the fourth wave of the pandemic, though he expressed the concern that COVID-19 cases in the country could remain at a high plateau.[431]

On 22 December 2021, Nedyalko Kalachev, the owner of the Cibalab laboratories, revealed that Omicron variant had been found in six virus samples.[432] Iva Hristova, head of the Center for Infectious and Parasitic Diseases, stated that the presence of Omicron will need to be confirmed through genomic sequencing, for which the private laboratories lack the technology, with precise findings expected to be available after the new year.[432] In an interview on 27 December 2021, mathematician Nikolay Vitanov estimated that Omicron is already in Bulgaria, believing that cases with this variant will start to rise by mid January 2022, with a fifth virus wave occurring in February 2022 as a result of Omicron's very high transmissibility and the still low vaccination coverage of the population.[433] On 2 January 2022, the health authorities confirmed the first 12 cases of the Omicron variant.[434][435] 7 of the infected had not been vaccinated, 5 had been fully vaccinated and none had received a booster dose.[434][435] By the second half of January 2022, Omicron had displaced Delta in terms of dominance in Bulgaria.[436][437] Lachezar Tomov cautioned in February 2022 that Bulgaria had so far failed to reverse any negative trends with regard to the major surges of the virus by relying mainly on herd immunity and without the imposition of new measures.[438]

The R0 number for the virus is believed to be able to reach values as high as 5 or 6 if the spread is uncontrolled,[12] rising to 7 and 9 in the case of the Delta variant,[430][439] with a potential reproduction factor of 15 with regard to Omicron.[440] A further caveat is that in the case of COVID-19, it may not be the best measure for the state of the epidemiological situation due to the importance of superspreaders.[441]

In Bulgaria the RO was estimated to be at 1.9 (with 10 people infecting 19 others) towards the end of October 2020,[442] between 1.2 and 1.3 in early March 2021[7] and around 1.1 on 22 March 2021 (the first day of the third lockdown).[442] On 13 May 2021, mathematician Nikolay Vitanov declared that the third wave in Bulgaria is ending, emphasizing the importance of the vaccinations and appraising the basic reproduction number to be at the record low 0.595.[443] Approximately one month later, on 11 June, it stood at 0.716.[444]

The effective reproduction number reached a value of 1.7 during the first weeks of the pandemic[445] and hovered at slightly above 1 in May 2020.[445] It is believed to have been constantly on the rise since 14 January 2021, exceeding 1 by early February 2021.[446] It was below 1 for the month of May 2021,[423] being calculated to be 0.81 around 6 May 2021[447] and 0.80 around 6 June 2021.[447] In mid July 2021, experts warned that the number is once again around 1[448] which was also ultimately assessed to be the beginning of a fourth wave,[449] and it reached a value of 1.5 in early August.[447] It continued to consistently exceed 1 during the next two months, being assessed to be at 1.3 around 22 October,[447] though it dropped to below 1 during November before starting to once again hover around that number towards the end of that month.[447] The R0 number remained at around or just below 1 during December before rising sharply and reaching 1.7 in January 2022.[447] It subsequently fell to slightly above 1 and was assessed as stable at 0.99 towards the end of the month.[447] It was estimated to be below to just below 1 during the whole of February 2022[447] and March 2022.[447]

The government has come under scrutiny for the delay in ordering a number of vaccines,[69][476] the lack of sufficient transparency regarding the quantities,[477] the call to give up on doses of the two RNA vaccines, for which Bulgaria had been eligible, during the initial pre-orders[478][479] as well as the reasons behind its decision to center its vaccination campaign on Oxford-AstraZeneca in particular.[480][481] In the case of the Oxford vaccine, due to the cheaper cost of AstraZeneca relative to the RNA vaccines and the former's easier storage requirements,[482] the authorities have mainly been criticized for allowing financial considerations to take precedence over health-related ones.[69] Concerns have also been raised due to the government not outlining a plan for creating special vaccination centers[483] and training additional personnel capable of administering vaccine shots,[484] which has contributed to a slow pace of the vaccinations.[16][95] The lack of expediency with the vaccinations has been assessed as entailing significant risks for the country being able to meet its economic growth targets for 2021[485] and has been deemed likely (in combination with the relaxing of many pandemic control measures during the month of April 2021) to considerably lessen the country's appeal as a summer destination for tourists due to a continuing high rate of infections.[486] As of late May 2021, only 45% of the vaccine doses delivered to Bulgaria had been administered, compared to an average for the EU of 85%.[262] In September 2021, Chief Health Inspector Angel Kunchev reiterated that if the vaccination coverage remains at a low level, Bulgaria will hardly see tourists visiting during 2022.[337]

Pulmonologist Kosta Kostov has been very critical of the way in which the vaccination campaign has been organized and implemented, regarding it as not premised on empathy,[23] being incredulous that people over 65 and clinically vulnerable individuals are in phase 4 rather than being the top priority targets[487] and maintaining that people who have recovered from the disease should not be vaccinated as long as there is an insufficient quantity of vaccines.[488] Similarly, Dimitrina Petkova, an expert on equality in health care, has characterized the vaccination plan as unfair to the elderly due to attaching a greater value on reducing the spread by vaccinating economically active young people rather than by focusing on especially vulnerable groups in order to save the most lives,[258] a sentiment echoed by caretaker Health Minister Stoycho Katsarov who considered its faulty approach in terms of prioritization and the issues with vaccine procurement to have resulted in the loss of 10 000 lives.[489]

The decision taken by the government on 19 February 2021 to set in motion the mass vaccination process has been criticized for inviting chaos,[102][490] with general practitioners complaining of a lack of vaccines provided to them for their registered patients who belong mainly to high-risk groups,[491][490] with most of the doses allocated to the hospitals for random vaccinations,[236][492] not allowing for thorough medical check-ups of the people prior to the administering of vaccines.[493] Concerns have also been raised that the citizens who had already received one shot may not be able to get their second injection as scheduled.[236] The shift in the modus operandi has been contested for its dubious legal basis due to being in apparent contradiction with the authorities' own phased approach to the vaccinations, entailing the prioritization of vulnerable groups such as the elderly,[490][494] and has been characterized as a desperate attempt to boost the vaccination statistics.[490] As of 1 April 2021, only 9% of the elderly and chronically ill had been vaccinated.[336] As of 18 May 2021, less than 20% of the people considered especially vulnerable had received at least one dose of vaccine.[495] By 24 June 2021, one third of care home residents had been administered at least one shot of vaccine.[426] The issue has resulted in media crossfires between Kostadin Angelov and his caretaker government successor, Stoycho Katsarov.[495]

The need for general practitioners to queue for vaccines for their patients in front of the regional health inspectorates has invited tension and been described as humiliating as well as an example of an inefficient time management.[496][497] In response to this issue, the caretaker government decided in May 2021 to set up logistical points for each municipality where regional health inspectorates are to deliver flasks with vaccines, taking into account the quantities requested by the general practitioners.[498]

Former Health Minister Kostadin Angelov has expressed criticism of those medical practitioners who have encouraged their patients not to get themselves vaccinated.[416]

In March 2021, some medical experts in Bulgaria characterized the temporary suspension of the vaccinations with Oxford Astra-Zeneca as an overreaction and potentially dangerous in terms of stoking fears among the already vaccinated[405] while in September 2021 caretaker Health Minister Stoycho Katsarov blamed Boyko Borisov's intervention at the time for reducing people's trust in this vaccine.[499]

The Expert Council on Obstetrics and Gynecology has courted controversy by strongly recommending against pregnant women receiving vaccines, contrary to the existing scientific evidence.[384]

A number of media sources have taken issue with the government's manner of reporting the official figures regarding the number of individuals who have been vaccinated, believing that it invites confusion.[1]

Concerns have been expressed regarding the lack of a targeted campaign to vaccinate the children aged 12 and over.[500]

The issuing of fake vaccine certificates by people working within the medical field has been noted as a concern,[501] with the media raising the alarm regarding such instances[502] and 14 such signals received by the office of the Chief Prosecutor as of early October 2021.[390]

The manner in which the "green certificates" were introduced by the authorities in October 2021 has been criticized by experts due to being a delayed measure,[503] the lack of a sufficient pre-warning, especially given the low rate of vaccination in Bulgaria,[504] for creating panic among citizens, also hampering the work of medical professionals,[505] for potentially encouraging the issuing of fake documents,[504] the inherent health risks due to people with far from completed vaccination courses being able to obtain them,[506] coupled with the scientifically suspect issuing of such documents based solely on antibody levels[507] and due to not being a sufficiently strict measure, serving as an inadequate substitute for a lockdown.[508]

Some of the vaccines that arrived Sofia on 26 December were subsequently transported to Plovdiv by using a Leki food industry minibus, and were then stored in a ZiL refrigerator on reaching their destination, which resulted in criticism and mockery on social media, but the Health Ministry cited examples of such reliance on the services of private companies not being an unusual practice in Western countries and maintained that all the proper guidelines had been observed.[509]

On 9 January 2021, the Ministry of Health revealed that it was conducting an urgent investigation after receiving information that councillors in Sandanski Municipality had already received vaccines despite not being part of the groups prioritized during the first phase, as stipulated by the vaccination plan.[510] The director of the hospital in Sandanski, Iliya Tonev, subsequently claimed that a number of the people who were to have priority in terms of vaccinations had ultimately decided against it, so appointments were set up with the councillors (who were among the volunteers in popularizing the Pfizer-BioNTech vaccine) at a short notice in order for the doses not to go to waste.[511] However, after the review of the facts, the Minister of Health was adamant that the protocols had not been adhered to in vaccinating 24 of the people, as there had been sufficient time for a proper redistribution of the vaccines, claiming that if he had the authority, he would have released the hospital director from his duties.[219][512]

In February 2021, chief national health inspector Angel Kunchev revealed that people holding anti-vaccination views had in a number of instances deliberately signed up for receiving their injections and then failed to show up in the hopes of sabotaging the vaccination process.[513] The online registration system for vaccinations has been subjected to hacker attacks.[514]

In late February 2021, a young couple from Pleven was refused vaccination because of not having proper health insurance. The Health Minister ordered that the case be looked into,[515] confirming that each Bulgarian citizen is eligible for vaccination regardless of his or her health insurance status.[516] Yordan Georgiev, the director of the St. Pantaleymon hospital where the situation had transpired, was criticized for not being familiar with the Health Ministry's policies, with journalists also drawing attention to the multitude of instances of British citizens without health insurance having received vaccinations in Bulgaria.[516] The man and the woman were subsequently invited by other hospitals in the city to be administered their doses.[516]

In March 2021, Angelov revealed that some people had been signing up to participate as electoral commission members (without intending to follow through with their commitments) just so that they could get themselves vaccinated.[517]

In May 2021, police had to be called after Turkish citizens, some of whom were also with Spanish passports, who had travelled across the border to make use of Bulgaria's "green corridors" attempted to receive a jab at a mobile vaccination point near the Regional Health Inspectorate of Bourgas.[518] According to Bulgarian legal regulations, only foreigners permanently residing in Bulgaria or those meeting certain criteria, such as foreign students enrolled at Bulgarian universities or members of diplomatic missions,[519] as well as those with dual citizenship are eligible to be vaccinated in the country.[518]

In September 2021, a group of vaccine sceptics self-styled as "Committee of Salvation" who demanded a document confirming that the vaccines are authorized to be administered in Bulgaria disrupted the proceedings at a mobile vaccination point at the entrance to the Sea Garden in Varna,[520] eventually causing it to discontinue its work.[521] The incident was strongly condemned by the Health Minister.[522]

Since late September 2021 banners proclaiming that COVID-19 is a hoax and opposing all the vaccines have been placed prominently near the Monument to the Tsar Liberator and the Old House of the National Parliament by members of the "People's Party the Truth and Only the Truth" (Bulgarian: "Народна партия Истината и само истината"), associated with Ventsislav Angelov, a candidate for president.[523] In early October Traycho Traychov, mayor of Sredets district that covers the area, insisted that the signs be removed, but the party organizers have been able to secure permission from the municipality regarding the continued display of the banners. The same signs had been ordered to be taken off in Rousse, Angelov's hometown, by the mayor of the city, Pencho Milkov, with some sources criticizing his Sofia counterpart Yordanka Fandakova for not following the same course of action.[524]

One of the controversial banners of the "People's Party the Truth and Only the Truth".

In October 2021, the police dismantled a criminal network operating across the whole country and involved in the issuing of fraudulent COVID-19 vaccine certificates, with four suspects being detained in Veliko Tarnovo. It was determined that at least five such documents had been provided, with two of the recipients no longer residing in the country.[525] People employed in a hospital in Kyustendil[526] and a paramedic from Yablanitsa[527] are also believed to be part of the scam. The issue has received attention in neighbouring Greece, as some Greek citizens have obtained such certificates, with the headquarters of a number of criminal groups involved in the practice believed to be in the city of Sandanski.[528]

On 20 October 2021, caretaker Minister of Education Nikolay Denkov was accosted by a number of sympathizers of the Vazrazhdane party who were protesting against the green certificates and other policies such as the wearing of face masks by schoolchildren.[529] One of the involved attempted to get physical with the educator, but the presence of police officers prevented an escalation of the situation.[530]

On 23 October 2021, Kostadin Kostadinov, leader of Vazrazhdane, posted a video on his Facebook profile, alleging that expired vaccines were being administered to Bulgarians.[531] The Ministry of Health refuted this, maintaining that there have been no instances of vaccines being used past their expiry date[532] and that EMA had changed the shelf life of the Pfizer vaccine from 6 to 9 months in accordance with the standard procedure.[533] On 24 October 2021, Boyko Borisov made the same allegation, as a result of which the Health Minister alerted the Prosecutor's Office in Sofia due to what he regarded as the spreading of fake news.[534]

In November 2021, a fraud scheme for COVID-19 vaccine passes in Sofia, involving Velichko Georgiev, a politician from the Patriotic Front coalition, was unravelled after a Nova TV investigation.[535] The immunity of Georgiev, who was a candidate to be a deputy in the National Parliament, was waived and he was expelled from the NFSB.[536] During the same month, police broke up another fake COVID-19 vaccine certificate network, operating in Asenovgrad and Rakovski, involved in the issuing of at least 250 such documents, arresting four people.[537]

In November 2021, chief health inspector Angel Kunchev who had been vaccinated with two doses tested positive for COVID-19. Fake news that he had been hospitalized in serious condition and lost the battle against the disease were subsequently spread on the Internet.[538][539]

On 31 December 2021, a few hours before New Year's Eve, a 53-year old former army serviceman was detained by the police at the Alexander of Battenberg Square in Sofia after expressing anti-vaccination views and threatening to detonate a grenade.[540]

In January 2022, controversial conspiracy theorist Ventsislav Angelov aggressively confronted and got into a serious physical altercation with a medical practitioner who had administered a Janssen vaccine, which was alleged to have contributed to a fatal outcome in the case of the recipient, and was subsequently arrested by the police.[541][542]

On 21 January 2022, it was reported that the chief prosecutor's office was in the process of investigating infectiologist Atanas Mangarov due to his allegations (refuted by the Ministry of Health) that more than 500 fatalities had occurred[543] as a direct result of the administration of vaccines.[350]

In February 2022, police broke up a network at a medical center in Sofia involved in the issuing of more than 3000 fraudulent green certificates.[544]

In December 2020, Bulgaria stated that it will take the initiative in securing vaccines for North Macedonia and other states from the Western Balkans,[545] but as of mid February 2021, with the country struggling to obtain enough vaccines for its own citizens, this had not materialized, generating critical headlines in the Macedonian[546][547] and Bulgarian media.[547][548] On 29 May 2021, it was confirmed that Bulgaria will donate 50,000 of its vaccine doses to North Macedonia as a "friendly gesture".[147]

In November 2021, the European Commissioner for Internal Market Thierry Breton visited Bulgaria to meet with caretaker Prime Minister Stefan Yanev, expressing full support for Bulgaria's fight against COVID-19 and offering help while also emphasizing that the low vaccination coverage in the country could potentially result in the creation of an additional variant of the virus, putting other EU citizens at risk.[549][550] European Commissioner for Health and Food Safety Stella Kyriakides voiced similar concerns in December 2021.[551]

A banner of The Representative Office of the European Commission in Sofia intended to popularize the vaccination campaign in Bulgaria, on which a young couple is depicted.

Another poster advertising the vaccination campaign, on which a man and his granddaughter are shown.

A sign in the Krasno selo district, encouraging Bulgarians to get themselves vaccinated.

A billboard in the Ilinden district with the message that the vaccine saves lives.

According to an April 2020 Gallup survey, over 75% of the citizens expressed support for the lockdown-related pandemic control measures taken by the government and the members of the National Operational Headquarters for the fight against the coronavirus in Bulgaria,[552] but the subsequent loosening of restrictions and the exponential rise in cases in October and November caused public support for the authorities' strategy to plummet to slightly over 30%.[553] In an Alpha Research survey conducted between 8 and 15 September 2021 24.2% of Bulgarians expressed approval of the caretaker government's performance in managing the pandemic and the vaccination campaign while 42% had a negative view.[554] In а Маrch 2022 Alpha Research survey 42.2% of Bulgarians rated the Petkov government's policies in relation to healthcare and the pandemic as successful while 55.6% regarded them as unsuccessful.[555]

While Bulgaria has historically been characterized by receptive attitudes to vaccines,[556] with the country having a long tradition of compulsory immunizations against certain diseases[339][557] and a high national vaccination coverage for children,[558] the lack of trust in the government and the health providers was from the outset believed likely to provide additional fuel for vaccine hesitancy attitudes, which have been regarded as pervasive in contemporary Bulgarian society,[559][560] with one January 2021 Gallup poll seeing 46% of interviewees declaring that they will not take a COVID-19 vaccine.[561] Prior to the pandemic, less than 4% of Bulgarian adults opted for the flu vaccine.[562] Nonetheless, in the first three months since the vaccinations began Bulgaria was roughly in line with the EU average, especially with other Eastern European countries, when it came to the people's dispositions towards the vaccines.[563][564]

An Exacta Research Group survey covering the period between 12 and 20 March 2021 revealed that the share of Bulgarians categorically ruling out vaccination against COVID-19 had fallen to below 40%.[565] However, in May 2021 the country still occupied the top spot among EU countries with regard to vaccine skepticism, according to data from Eurofound.[262][566] In September 2021, in another Gallup survey, 45% of the respondents declared that they had not been vaccinated and do not intend to do so.[567] А nation-wide opinion sampling of 1151 adult Bulgarian citizens conducted by the Bulgarian Academy of Sciences, the University of National and World Economy, Bulgarian Sociological Association and the Union of Economists of Bulgaria in mid 2021 showed that while 60% of respondents supported a full lockdown if necessary, a plurality (44.3 vs. 22.4%) preferred a natural infection to a vaccine if having to choose between the two, with 27.5 neutral regarding these options.[568]

There have been regional differences regarding the interest in the vaccinations[72] and people residing in smaller cities and villages have been less enthusiastic about the "green corridors".[569] Education correlates positively with a desire for vaccination,[565] with university educated people residing in the capital and aged over 40 being the most willing.[570]

Skepticism regarding vaccines is a major issue when it comes to the Romani people,[571][572] though the interest among the members of this group has increased, with the one-dose Janssen vaccine being the most popular.[573]

An April 2021 Gallup survey revealed that 50% of Bulgarians expressed qualified support for COVID-19 vaccine passports while 43% were opposed.[403] A Darik Radio poll of over 1300 Bulgarians conducted shortly after the October 2021 introduction of the green certificate saw 32.6% of the respondents in favor of the pandemic control measures and approving of the vaccine pass, 28% accepting of the non-pharmaceutical interventions, but regarding the green pass in particular to be discriminatory, 32.16% totally opposed to it and 7% preferring a full lockdown.[574] According to sociologist Dimitar Ganev from "Trend", as of January 2022, the majority of the country's citizens remained negatively disposed towards the green pass requirement.[575]

According to a March 2021 survey, 65.8% of the general practitioners' patients preferred one of the two RNA vaccines, 28.9% expressed no preference while 5.3% gave the nod to Oxford-AstraZeneca,[576] with the Pfizer-BioNTech vaccine being the most in demand as part of the "green corridors".[577] Since its approval, Janssen has gradually started to overtake Moderna in terms of popularity, presumably due to it being one-shot, with 151 391 out of 647 382 administered doses between 12 May and 7 September being with this vaccine.[578] It was the only one out of the four vaccines that was used more frequently in September 2021 compared to June 2021.[129]

The possibly false belief among many Bulgarians that they have already had the virus and recovered from it has also been identified as a further contributing factor to the vaccine skepticism,[35] being the most selected option in a Gallup poll from March 2022.[579] Concerns about the vaccine safety and the side effects remain important reasons.[580]

In a prevailing climate of "informational anarchy", as characterized by social anthropologist Haralan Alexandrov,[581] the media in Bulgaria have been blamed for giving undue weight to vaccine skeptics, including those within the medical community, in their coverage of COVID-19,[582] thus mainstreaming a variety of fringe or pseudoscientific views,[583] as well as refraining from showing the reality on the ground inside the COVID-19 hospital wards.[564]

In sociologist Aleksandar Marinov's view, the discordant tone between the public institutions in the country is believed to have also negatively affected trust in the vaccines[584] while in journalist Yassen Boyadzhiev's opinion politicians such as Kiril Petkov who are pro-vaccination have been overly accommodating of ill-intentioned vaccine skeptics and have made the mistake to include them in discussion groups on pandemic control measures.[585]

The business sector has also been criticized for not being actively engaged in agitating for vaccinations.[586]

The country as a whole, which faced high levels of intra-societal polarization during 2020 and 2021,[587] has been identified as especially susceptible to disinformation warfare due to a lack of a developed infrastructure to guard against such tactics.[588] Such propaganda campaigns are sometimes driven from abroad,[589][590] with some sources blaming the Chinese[591] and Russian influence in that regard, seeing the anti-vaccine rhetoric as part of an orchestrated campaign against the country's future in the EU.[592] According to Kalin Yanakiev, a lecturer in philosophy from Sofia University, strong anti-vaccine attitudes in Bulgaria tend to go hand in hand with anti-Western views, Russophilia, nationalism and identification with the Orthodox faith.[593]

Due to the vaccine trepidations and the proliferation of conspiracy theories in Bulgaria pertaining to the nature of the virus itself,[594] an information and explanation campaign pertaining to the vaccines and directed at the general public, including educated groups such as teachers,[595] and the physicians themselves, a low percentage of whom have recommended vaccination to their patients,[596] with 20.8% of medical personnel immunized as of 27 June 2021,[597] has been identified by some journalists as the real challenge with regard to vaccinating a sufficient number of people, so that herd immunity could be reached.[598]

Public vaccinations of politicians have also been regarded as potentially useful in allaying people's fears of the COVID-19 vaccines.[56]

The Representative Office of the European Commission in Sofia has pledged cooperation with the Ministry of Health in popularizing the vaccination campaign.[599] In June 2021, European Commissioner for Health and Food Safety Stella Kyriakides visited Bulgaria and discussed the country's vaccination program as well as suitable measures to broaden the appeal of the vaccines.[408] with the WHO also offering financial support.[600] Hotels and restaurants in the Albena resort achieved a high degree of vaccination coverage as a result of the provision of financial incentives by the management.[582][601]

A poster of the Vazrazhdane party, opposing mask mandates, lockdowns and mandatory vaccinations in Bulgaria.

In July 2021, as part of its strategy for encouraging vaccinations, the Ministry of Education took the decision to offer two additional days of paid leave to educators who are vaccinated while the schools where at least 70% of staff members are vaccinated will receive a certificate for contribution to public health.[602]

Food vouchers have been offered to vaccinated people making purchases in supermarkets,[603] though this strategy has not made a significant difference in encouraging vaccine uptake.[590]

The offering of financial bonuses is believed likely to yield dividends in increasing the vaccination drive among the generally less affluent Romanis.[604]

In September 2021, caretaker Minister of Tourism Stella Baltova announced that the Health Ministry will organize draws for people who are vaccinated.[605] All Bulgarian citizens over the age of 12 who were vaccinated between 30 September and 31 October 2021 were able to enter a draw, organized by the Ministry of Health, for one of 102 smartphones,[606] with the youngest participant aged 12 and the oldest 92.[607]

In November 2021, economist Georgi Angelov suggested that each vaccinated retiree receive 1000 leva as a bonus.[608]

Some public figures such as Health Inspector Angel Kunchev have urged that vaccinations be made mandatory for medical personnel and social workers in frequent contact with elderly people[609] while former head of Pirogov Hospital Asen Baltov has expressed the opinion that in addition to the latter two categories, teachers, police officers and army personnel should be required to complete a vaccination course.[610] Former caretaker Health Minister Stoycho Katsarov has also been sympathetic to the idea of people with certain occupations being subject to obligatory vaccinations.[611] While strongly encouraging all Bulgarians to take a COVID-19 vaccine, in January 2022 Prime Minister Kiril Petkov ruled out the option of his government introducing mandatory vaccination.[612]

In December 2021, the National Council of the Religious Communities in Bulgaria began working together with the Ministry of Health with the purpose of raising awareness regarding the benefits of vaccination.[613]

On 23 December 2021, newly elected Prime Minister Kiril Petkov announced that each person over the age of 65 years who completes the vaccination course or has already received a booster dose will have 75 leva added to the next pension he/she is to receive. This initiative is set to run between 1 February and 30 June 2022[614] and it was subsequently confirmed that it will include retirees below the age of 65 as well.[615]

The controversial banners near the Old House of the National Parliament and the Monument to the Tsar Liberator, opposing all COVID-19 vaccines. The text in large blue letters expresses the opposite sentiment, reading "We [the authors] are illiterate populists and liars."

Many politicians have been reluctant to broach the subject of vaccines.[616] According to analysis posted by journalist Nikolay Lavchiev, only two parties - GERB and DPS - could be credibly described as explicitly pro-vaccination in terms of actively encouraging their sympathizers to get a vaccine.[205] Parties on the far right, such as Vazrazhdane, have expressed strong reservations regarding the vaccinations,[600] even though a number of the party's deputies in the National Parliament have been administered COVID-19 vaccines.[617] The mainstream ITN has also been accused by some sources of dabbling in anti-vaccine rhetoric.[35][618]

The 47th National Assembly began its sessions without a green certificate requirement for the deputies,[619] but on his election as new Prime Minister in December 2021 Kiril Petkov introduced such a measure for the Council of Ministers,[620] which entered into force in February 2022.[621]

On 7 January 2022, the deputies took the decision that access to the National Parliament will be conditional upon the possession of a green certificate,[622] starting from 24 January.[623] The members of ITN and Vazrazhdane did not participate in the vote.[623] Due to the lack of a specified punitive mechanism for non-compliance with this requirement, there has been no enforcement by the National Security Service, with a number of deputies continuing to attend sessions without such a document.[624]

A small protest against the vaccinations took place on 17 March 2021, in front of the Ministry of Health,[625] while a similar demonstration occurred on 29 May 2021, in front of a vaccination began at Yuzhen Park.[626] Small-scale protests against mandatory vaccinations and pandemic control measures continued to occur in August[627] and September.[628] Such protests increased in intensity after green certificates were mandated for indoor public places in October 2021.[529] On 12 January 2022, Vazrazhdane held a large demonstration against the green certificates that took place in the vicinity in the National Parliament, during which sympathizers of the party attempted to break through the police lines and enter the building.[629] On 23 February 2022, the party organized a similar protest while also expressing approval that on 21 February the government had vowed to gradually phase out the vaccine pass.[630]

A drawing covering the topic of the COVID-19 vaccination, appearing to give a nod to conspiracy theories regarding the vaccines.