Every year, an estimated 5 to 20 percent of the population gets the flu, and for those that do, it’s never a fun ride. Fever, aches, and debilitating fatigue are the norm, at least for the lucky ones. The not so lucky may become part of the approximately 36,000 deaths or 200,000 hospitalizations that also occur.
Because of these outcomes, as well the numerous days lost at work, we’re consistently reminded to our get flu vaccine. But many people refrain. Some may hold back because of last year’s outcome—the vaccine was a poor match to the circulating virus and many still became sick. Elderly people may have heard about a recent study that calls to question the vaccine’s effectiveness in their population. And others simply want to avoid the painful stick while keeping the twenty odd bucks in their pocket.
But is not getting vaccinated a gamble worth taking? Who should get the flu shot and who should roll the dice?
Best Guess
Unlike other vaccines, the flu vaccine is formulated differently each year, and it’s a bit of a guessing game as to which strains it will contain. The vaccine consists of three flu viruses: two A types and a B type. The B type doesn’t change very much from year to year, but the A type can mutate rapidly. So every year, researchers have to forecast which viruses they think will be present the following season. These forecasts are based on the best scientific evidence, but sometimes aren’t accurate; last year for instance, the flu shot was poorly matched to the virus that ended up being the most prevalent. Some people who received the vaccine still got the flu, although there is evidence that symptoms were milder than had they not received it.
This makes it seem like a bit of a gamble. But a recent study published in Pediatrics found that even during years with a bad vaccine match, the flu shot can protect kids. The researchers estimate that fully vaccinated children were half as likely to get the flu as those who received no vaccine.
Conflicting Reports
Children, the elderly, and people with pre-existing conditions are usually considered high priority groups for the flu vaccines. Especially since the elderly population is most likely to suffer serious complications from the flu, the vaccine has been seen as a lifesaver. But a recent report cast a shadow on just how effective it is in preventing flu complications in this population. One of the major causes of death in older people who get the flu is pneumonia. A recent study in the Lancet found that the ability of the vaccine to prevent serious pneumonia in older people might have been overestimated. The researchers found that in previous studies, the older people who got the vaccine were healthier than those who didn’t; it wasn’t the vaccine that prevented the pneumonia, it was the fact that the population under study was generally healthier. When this was taken into account, the researchers found that the flu shot didn’t reduce the risk of getting pneumonia in the older population.
However, the study didn’t look at the main purpose of the vaccine—preventing the flu. Although an older person’s immune reaction to the flu vaccine may not be as strong as a young person’s, there is much evidence pointing to the ability of the vaccine to prevent the flu in general. Its ability to protect the elderly population from mortality due to flu complications is less clear.
What About Kids?
Children are also a priority group for the vaccine, but many parents are loath to add another vaccine to the list. And recent research, including a recent study finding that the flu vaccine was not associated with reduced hospitalizations or doctor’s visits for kids, may add to their reasons to avoid this year’s shot. But because study design can greatly alter findings, one of the most comprehensive ways to look at the effectiveness of the vaccine in children to is cull all the research and then analyze it. This is what researchers at the Cochrane Collaboration did in a 2008 meta-analysis. Looking at fifty-one studies, including sixteen randomized controlled trials (considered the gold standard in trial design), they found that activated vaccines were effective in preventing confirmed influenza in 82 percent of children older than two, compared to kids that received a placebo or no intervention at all. The effectiveness, which measures prevention of influenza-like disease, was lower—33 percent—but the vaccine still conferred a benefit.
