The seasonal flu vaccine is associated with a 19% reduction in the rate of first heart attack and early vaccination in the fall further increases the benefits, found a study published in CMAJ (Canadian Medical Association Journal).
As heart attacks increase significantly in winter when pneumonia and flu are prevalent, it has been suggested there may be a link between respiratory infections and heart attacks.
The study, by researchers from the United Kingdom, looked at 78,706 patients aged 40 years or older from 379 family practices in England and Wales. Of the total, 16,012 had had a heart attack and 8,472 of these patients had been vaccinated. The researchers found that influenza vaccination within the past year was associated with a significantly reduced rate of heart attack. However, pneumococcal vaccination showed no additional benefit.
Early vaccination for influenza (between September and mid-November) was associated with a higher (21%) reduction in the rate of heart attacks compared with late vaccination which was associated with a 12% reduction.
"Our findings reinforce current recommendations for annual influenza vaccination of target groups, with a potential added benefit for prevention of acute myocardial infarction in those without established cardiovascular disease," writes Dr. Niroshan Siriwardena, University of Lincoln, United Kingdom with coauthors Stella Gwini and Carol Coupland. "This benefit may lead to an increase in suboptimal rates of vaccination, particularly among younger patients."
Because people with risk factors for heart attacks were more likely to be vaccinated than those with no risk factors, the researchers adjusted for possible bias in the sample.
They conclude that if additional research shows a similar effect, it could lead to changes in the recommended indications for and timing of vaccinations.
- A. N. Siriwardena, S. M. Gwini, C. A. C. Coupland. Influenza vaccination, pneumococcal vaccination and risk of acute myocardial infarction: matched case-control study. Canadian Medical Association Journal, 2010; 182 (15): 1617 DOI: 10.1503/cmaj.091891
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