THE QUESTION Besides preventing the flu, might the flu vaccine also prevent serious heart problems?
THIS STUDY analyzed data from five studies, involving 6,469 people (average age, 67), including 2,172 with cardiac disease. All had been randomly assigned to get either the influenza vaccine (by injection or nasal spray) or a placebo. Over the next eight months, 246 people experienced a major cardiovascular problem, such as a heart attack, stroke, heart failure or a blocked coronary artery, and 95 deaths were attributed to a cardiovascular cause. People who had been vaccinated for the flu were 36 percent less likely to have had a subsequent heart problem and 19 percent less likely to have died from one than were those who had been given the placebo. Among people with heart disease, those who got the vaccine rather than the placebo reduced their risk for another incident by 55 percent.
WHO MAY BE AFFECTED? Anyone who gets vaccinated for the flu and people at risk for cardiovascular problems, especially older people. Some experts believe that the inflammation that develops in response to the flu, reflected in the overall aches and pains people feel, can lead to cardiovascular problems, perhaps dislodging plaque that has built up in an artery or inflaming the heart itself; thus, a vaccine that prevents the flu may in turn prevent heart problems. During last year’s flu season, 42 percent of adults in the United States, including 67 percent of those age 65 and older, were vaccinated against the flu.
CAVEATS Estimations of risk were based on a relatively small number of cardiovascular incidents and deaths. People in the study had varying degrees of cardiovascular risk. Analysis did not indicate how the vaccine affected specific heart problems.
FIND THIS STUDY Oct. 23/30 issue of JAMA at www.jama.com.
The research described in Quick Study comes from credible, peer-reviewed journals. Nonetheless, conclusive evidence about a treatment's effectiveness is rarely found in a single study. Anyone considering changing or beginning treatment of any kind should consult with a physician.