Flu Season Continues; Seniors Hit Hard

January 25, 2013 -- Influenza continues to cause a lot of illness across the country and flu-related hospitalization and death indicators have increased sharply in recent weeks. The latest FluView report shows some indicators decreasing while others continue to rise and underscores again that this flu season is taking the heaviest toll on people 65 and older. CDC is urging seniors to seek treatment for flu-like symptoms promptly and for physicians to treat flu with antiviral medications in these high risk patients as early as possible to avert more serious outcomes.

“It’s not surprising to see severity indicators increasing at this point in the season because hospitalizations and deaths typically lag behind other flu activity indicators - but the increases are visually dramatic,” says CDC’s Dr. Lyn Finelli. “The overall picture is clear. This season is severe for seniors, who are being hit hardest in terms of serious illnesses and deaths. It’s really important that these people seek care and get treated promptly.” Finelli is Lead for the Surveillance and Outbreak Response Team in CDC’s Influenza Division.

Antiviral treatment, started as early as possible after becoming ill with influenza, is recommended for any patients with confirmed or suspected influenza who are hospitalized, seriously ill, or ill and at high risk of serious influenza-related complications, including young children, people 65 and older, people with certain underlying medical conditions and pregnant women. Treatment should begin as soon as influenza is suspected, regardless of vaccination status or rapid test results and should not be delayed for confirmatory testing.

According to Finelli, the pattern of severity among seniors this season is similar to some previous seasons during which influenza A (H3N2) viruses predominated. On average, CDC estimates that seniors account for about 60 percent of flu-related hospitalizations and 90 percent of flu-related deaths. “We are well within normal parameters for an H3N2-predominant influenza season, but the high amount of flu activity still translates into a lot of people being sick and some severely sick,” says Finelli.

The proportion of deaths due to pneumonia and influenza (P & I) reported through the 122 Cities Mortality Reporting System is significantly elevated this week (9.8%), up considerably from last (8.4%), making this the third consecutive week that the proportion has been above epidemic threshold. (The epidemic threshold for Week 3 is 7.3%). Finelli explains, “This is the highest we’ve seen P & I go in nearly a decade, but it’s comparable to recorded percentages for past severe seasons, including 2003-2004 when P&I reached 10%, 1999-2000 when it reached 11.2%, 1998-1999 when it reached 9.7%, and 1997-1998 when it reached 9.8%. So yes, it’s a severe season, but it’s certainly not unprecedented for seasonal influenza.”

Another interesting benchmark for the season, according to Finelli, is the hospitalization rate for seniors. Influenza-related hospitalizations are assessed cumulatively throughout the season, and so the rate of hospitalization is expected to increase each week during flu season, as more flu-related hospitalizations are reported. During the first half of January 2013, the hospitalization rate for people 65 years and older climbed from just under 50 hospitalizations per 100,000 people (week ending December 29, 2012), to almost 98 hospitalizations per 100,000 people (week ending January 19, 2013). Previously, the highest hospitalization rate among seniors was 73.7 hospitalizations recorded during the 2007-2008 influenza season. But Finelli cautions: “CDC only began collecting this data for seniors in 2007 so it’s difficult to make the same kind of historical comparisons that we can for mortality.”

"Fortunately, the proportion of visits to doctors for influenza-like illness – a key illness indicator – seems to be leveling off," says Finelli. Specifically influenza-like illness (ILI) activity is declining in the South, Southeast, New England and the Midwest. While the Southwest, Mid-Atlantic and the Northwest of the country are still on the upswing. The percentage of respiratory specimens testing positive for influenza is down again, continuing an overall downward trend observed during recent weeks.

As long as activity continues, however, CDC is urging people who are at high risk of complications from flu – especially people 65 and older – to seek treatment promptly if they get flu-like symptoms. “While vaccination offers the best prevention against influenza, we know flu vaccine tends to works less well in seniors than in younger people because human immune systems weaken with age,” says Finelli. Early vaccine effectiveness (VE) estimates showing vaccine effectiveness of about 60% this season were not adjusted for age. CDC has cautioned that the VE number for seniors specifically may be substantially lower than 60%. “Thus even seniors who got vaccinated may get influenza. And because flu infection can be serious in this group of people, it’s important that they seek medical treatment as soon as symptoms appear."

According to Finelli, older adults often delay seeking medical treatment, but antiviral treatment of flu works best when started as soon as possible after symptoms develop. Antiviral drugs are prescription medicines that can shorten the time of illness and lessen symptoms, but most importantly, they can reduce serious complications from flu infection, including hospitalizations, intensive care unit (ICU) admissions, and deaths. “In the clinical setting,” Finelli says, “there is evidence that these drugs can make a difference between a milder illness and a hospital stay.”

Also, CDC routinely recommends that vaccination efforts continue as long as influenza viruses are circulating. At this time, some vaccine providers may have exhausted their vaccine supplies, while others may have remaining supplies of vaccine. People seeking vaccination may need to call more than one provider to locate vaccine. The Flu Vaccine Finder at may be helpful.

In addition to vaccination and antiviral drugs, everyday actions can help mitigate the risk of infection. Flu spreads mainly in droplets expelled when people with flu cough, sneeze or talk. As always, stay away from people who are sick. If you are sick, stay home to avoid spreading your illness to others.