Current flu vaccine less effective in the elderly, CDC says

Vaccination containers pass through a machine that will individually photograph vaccines for quality control on the assembly line at the Novartis flu vaccine manufacturing facility in Holly Springs, N.C., November 24, 2009. REUTERS/Jason Arthurs

Older people who received this season's flu shot appear to be less protected from the illness than younger people who were vaccinated. As a result, early flu treatment is especially important for anyone in this age group who shows flu symptoms, according to a new report from the Centers for Disease Control and Prevention (CDC).

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The results show adults ages 65 and over who got this season's flu shot were just as likely to visit the doctor for flu symptoms as older adults who weren't vaccinated.

By contrast, getting the flu shot reduced the risk of visiting the doctor for flu by about 50 to 60 percent in people from other age groups.

Nevertheless, older people are still advised to get a flu shot, the CDC says. The vaccine's effectiveness can vary from season to season, and person to person. During some years, the flu vaccine has been found to provide significant protection for older adults; during other years, no protection has been seen, said Erin Burns, a communications officer at the CDC's Influenza Division.

The new report only looked at whether this season's flu vaccine reduced the risk of doctors' visits for flu, and didn't examine hospitalizations for more severe flu illnesses. Some research shows that the flu vaccination can reduce the severity of illness in older people who do get sick. A 2011 study found that older people who received a flu shot were 61 percent less likely to be hospitalized for flu-like illness.

"While influenza vaccine is not perfect, overall, the evidence supports the public health benefit of vaccination," Burns said. "Vaccination is particularly important for people 65 and older who are especially vulnerable to serious illness and death, despite the fact that the vaccine may not work as well in this age group."

Because of their increased risk for flu complications, it's important for elderly people to seek treatment quickly if they develop flu symptoms, including fever, cough, body aches, headache, chills and fatigue. Antiviral medications for flu work best if they're given within 48 hours of the start of symptoms.

"Aging and chronic health problems can diminish the body’s ability to mount a protective immune response after influenza vaccination, which can result in lower levels of vaccine effectiveness in some older people," Burns said. But Burns notes that people ages 65 and older are a heterogeneous group, and some individuals have very responsive immune systems.

This year's flu season has been a particularly bad one for the elderly. Of the 8,953 people hospitalized for flu so far, more than half have been 65 or older, the CDC said. [See Why Is This Year's Flu Season So Bad?]

The new report examined the flu vaccine's effectiveness in 2,697 people between Dec. 2, 2012 and Jan. 19, 2013. When considering all age groups, the vaccine was 56 percent effective, meaning it reduced the risk of a doctor's visit for flu by 56 percent. This new estimate for the vaccine's effectiveness is slightly lower than an estimate given earlier this year, which said the vaccine was 62 percent effective.

The flu shot is recommended for everyone ages 6 months and older.

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