Seasonal Flu Vaccine Lowers Heart Attack Risk in Adults, U.K. Study Finds
Adults vaccinated for seasonal influenza were less likely to suffer heart attacks, according to a U.K. study that may provide additional motivation to people considering the yearly shot.
People at least 40 years old who were vaccinated during the flu season showed a 20 percent reduction in first heart attacks within a year, compared with patients who didn’t get shots, researchers said today in the Canadian Medical Association Journal. People who received vaccinations early in the season showed the greatest benefit.
Respiratory infections have been shown to trigger heart attacks, for reasons unclear to scientists. One theory is that infections cause plaque build-up in arteries to rupture, triggering blood clots. Earlier studies examining the protection offered by flu shots produced mixed results. The new research may spur more people to get vaccinated, the scientists said.
“Our findings reinforce current recommendations for annual influenza vaccination of target groups,” wrote the authors, led by A. Niroshan Siriwardena of the University of Lincoln, in Lincoln, England.
The reduction in attacks was 21 percent for people who got shots from September to mid-November, during the early part of the flu season, compared with 12 percent for vaccinations received later in the season, the scientists reported.
Pneumonia Vaccine
If studies confirm that giving the shot earlier in the season reduces heart attacks, health officials may change their recommendations for when vaccinations are offered, the authors wrote. A vaccine against pneumonia didn’t confer a similar drop in heart attacks, the study found.
The researchers examined records of 78,706 patients ages 40 and older in England and Wales from 2001 to 2007. The study looked at vaccination rates of 16,012 people who had heart attacks and 62,694 patients of similar age and background who didn’t. The research excluded patients whose attacks weren’t their first.
Heart attacks are more likely to occur in winter months, when flu spreads and pneumonia rates are highest. Flu in the northern hemisphere typically peaks from November through March.
Vaccinations are recommended for everyone in the U.S. over six months of age. Adults with chronic health conditions and those at risk for heart attacks are especially encouraged to get vaccinated, according to the U.S. Centers for Disease Control and Prevention, based in Atlanta.
Evolving Virus
Influenza is a rapidly evolving virus, and the severity of the season depends on which strains are circulating and how well a population has been inoculated. Annual deaths associated with seasonal flu ranged from 3,349 to 48,614 during the last 30 years, according to the CDC. About 90 percent of flu-related deaths are in people ages 65 or older.
The seasonal flu vaccines made by Paris-based Sanofi- Aventis SA, London-based AstraZeneca Plc and Basel, Switzerland- based Novartis AG each protect against the three strains of flu that scientists predict are most likely to circulate. The new H1N1 strain that emerged last year is included in this year’s shot.
To contact the reporter on this story: Tom Randall in New York at trandall6@bloomberg.net.
To contact the editor responsible for this story: Reg Gale at rgale5@bloomberg.net.
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