Flu shots may reduce heart attack risk in some adults

Australian researchers found the influenza vaccine may reduce the risk of heart attacks in middle-aged people with narrowed arteries by almost half, according to a study recently published in Heart.

The researchers sought to determine if flu is an unrecognized, but clinically important, contributing factor to the risk for heart attacks. Previously published studies suggest the flu increases the risk of death from all causes and the risk of hospitalization for respiratory and cardiovascular problems.

The research team assessed 559 patients over the age of 40 who were referred to a tertiary hospital during consecutive winters in 2008 through 2010. Out of the patients examined, 275 sustained a heart attack and 284 did not. The team found that 12.4 percent of the heart attack patients recently had flu while less than seven percent had flu in the comparison group. Half of the patients examined had the flu vaccine that year.

The study found that vaccination against flu decreased the risk of heart attack by 45 percent. Prior research suggests that influenza and other infections may encourage blood to thicken or prompt an inflammatory response in diseased arteries, potentially leading to a blockage.

Individuals between the ages of 50 and 64 are not routinely vaccinated in the national flu vaccination programs in the U.K. or Australia. While extending the vaccination program to that age group has been considered before, potential limiting effects on cardiovascular disease were never taken into account.

"As such, even a small effect of influenza vaccination in preventing (heart attacks) may have significant population health gains," the authors said.

The researchers called for the matter to be further explored.