The abstract for this study says that the researchers reviewed data from 39 studies.

These 39 studies were completed between 1932 and 2008 for the purpose of understanding potential links between flu and heart deaths.

All 39 of these studies, over 66 years, say that entire populations showed a rise in deaths due to heart disease or heart attacks when influenza viruses were circulating.

How much more evidence does anyone need to get a seasonal flu shot?

ABC News

“ Influenza can help trigger heart attacks and may account for a 35 percent to 50 percent rise in heart attack deaths during flu season, British researchers reported on Monday.

“While a flu vaccine can prevent these deaths, fewer than half of the most vulnerable heart patients in Britain actually get a flu vaccine every year, however, they said.

“We believe influenza vaccination should be encouraged wherever indicated, especially in those people with existing cardiovascular disease,” Charlotte Warren-Gash of University College London and colleagues wrote in the journal Lancet Infectious Diseases.

“Further evidence is needed on the effectiveness of influenza vaccines to reduce the risk of cardiac events in people without established vascular disease.”

Source: ABC News, September 22, 2009

Citation: Lancet Infectious Diseases, September 21, 2009