The incidence of heart attack rises sharply in the winter, when respiratory diseases such as influenza and pneumonia are rife. This observation has led to the suggestion that there may be a link between respiratory infections and heart attack. Researchers from the United Kingdom investigated this link by studying 78706 patients aged 40 and over, 16012 of whom had had a heart attack and 8472 had received a seasonal flu shot. Results showed that people who had been vaccinated against the flu were significantly less likely to have a heart attack than those who had not. Being vaccinated early in the flu season (between September and mid-November) was shown to reduce the risk of heart attack by 21%, while being vaccinated later on in the season was associated with a 12% reduction. Pneumococcal vaccination had no effect on heart attack risk. "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," concluded study leader Dr Niroshan Siriwardena, Professor in Primary and Prehospital Health Care at the University of Lincoln.