Each year the flu puts more than 200,000 Americans in the hospital and causes anywhere from 3,000 to 49,000 deaths. With the exception of the H1N1 flu (also called swine flu) in 2009, most of these deaths occur in people over 65. But even for healthy younger people, the flu—characterized by high fever, body aches, headaches and coughing—can be rough.
The Centers for Disease Control and Prevention (CDC) recommend that everybody over six months of age get vaccinated. It’s especially important for people 65 and older, anyone who has a chronic condition (such as lung or heart disease, diabetes, cancer or HIV infection), pregnant women, people on immunosuppressive drugs and healthcare workers.
Mid-October through November is a good time to get it. Flu epidemics usually begin in January or February, and it takes a few weeks to develop immunity from the vaccination. Besides the familiar injection, a nasal spray flu vaccine is also approved for people under 50.
Still, the vaccine doesn’t guarantee that you won’t get the flu. An analysis of 31 studies covering 12 flu seasons, reported in Lancet Infectious Diseases, found that the most widely used flu vaccine in the U.S was just 59 percent effective, on average, for people 18 to 65. There were not enough data about older people, but there’s reason to believe the vaccine may be even less effective in them.
Unfortunately, many media reports interpreted this to mean that the flu vaccine is no good. But the results weren’t too surprising given that every year scientists have to predict months in advance which strains of flu virus will predominate in the next flu season in order to develop the vaccine in time (flu viruses are constantly mutating, even within a current flu season). If Mother Nature outwits the prediction—that is, if there isn’t a close match between the strains of the virus selected for the vaccine and the actual circulating viruses—the effectiveness of the vaccine drops.
Then again, as shown in a study published in Vaccine in 2010, even when the match is incomplete, the vaccine still reduces the chance of getting infected and, if you do get sick, the severity of the illness—as well as hospitalizations from the flu and pneumonia (a life-threatening complication of the flu).
What’s more, how well the flu vaccine works varies from person to person. It causes your body to develop antibodies against the virus—but people who are old and frail, are immune-compromised and/or have a chronic illness don’t have as robust an immune response to the vaccine and thus may not be as well protected. Being overweight may also decrease your vaccine response and make you less able to fight the flu if you do get infected. On the other hand, some research has shown that getting the vaccine annually may provide cumulative benefits in older people—more reason not to skip a year.
Your best shot at protection
Even though the flu vaccine won’t keep everyone from getting sick, it lowers the risk and—this is key—helps prevent potentially fatal complications. It also reduces the number of people who can spread the virus (thus increasing what’s called “herd immunity”).