Does the Flu Vaccine Work?

The CDC recommends that every person receive the H1N1 flu vaccine once it becomes openly available, but many individuals are opting not to get it.  The reasons for this include misgivings about the vaccine’s safety and a general ambivalence about the severity of the swine flu virus.  Few, however, doubt the efficacy of the vaccine itself.  Vaccines are considered to be one of the wonders of modern medicine, responsible for saving millions of lives and virtually eradicating a number of diseases, like polio and mumps.  However, the influenza vaccine does not have the same proven track record as these others and our reliance on it may be preventing us from finding more effective means of combating the disease.

The reason we believe the influenza vaccine is effective at preventing the illness is that a number of flawed medical studies have told us so.  These studies are not flawed in that they are scientifically inaccurate, rather they tell partial truths and fail to take into account possible confounding factors.  Studies have shown that people who get the flu shot in the fall are half as likely to die later that winter, but with flu accounting for only a small fraction of deaths in the United States each year, it is possible that scientists have failed to consider other non-flu-related causes of death.

Lisa Jackson, a physician with the Group Health Research Center, suggests another reason for the discrepancy, the “healthy user effect.” In short, people that are in good health choose to get vaccinated, while those who are more susceptible to the illness choose not to or are unable to.  They cite one of their studies as proof.  After examining a large group of individuals 65 and over that got the vaccine and did not, researchers found that the risk of dying from any cause in the non-flu season for people that did not get vaccinated was 60% higher, suggesting that healthier people are more likely to get vaccinated.  Thus, the benefits of the vaccine we have touted for so long may only be the effects of a successful campaign to convince healthy people to get vaccinated instead of any real immunity that is confered to at-risk individuals.

Though it may seem inconsequential – so what if the positive effects of immunization have been inflated – our reliance on a potentially ineffectual vaccine diverts resources from other means of prevention.  This is particularly worrisome for the elderly, for whom some studies have shown the vaccine to be ineffective, and in the face of a swine flu pandemic, young people who are at a higher risk of falling life-threateningly ill this year.  The only way to determine if the vaccine is working is to conduct clinical trials, but some doctors wrestle with the idea of withholding the vaccine from at-risk individuals.