Flu shot effectiveness is questioned in new study

Annual flu shots protect only about 59 percent of the population — far less than previously thought — according to a new study led by University of Minnesota researchers.

The study found “major holes and gaps” in the vaccine given to tens of millions of Americans every year to prevent influenza and its complications, said Michael Osterholm, the lead scientist and head of the university’s Center for Infectious Disease Research and Policy.

But until a better vaccine comes along, Osterholm said, 59 percent “is a lot better than zero.”

In the past, experts have estimated that annual flu shots protect 70 to 90 percent of the population. But the new analysis found that on average, the vaccine worked on about 59 percent of adults younger than 65.

In fact, flu vaccines may have had little, if any, effect during some flu seasons, according to the report, which was published Tuesday. The most common flu shot had no noticeable impact in four out of 12 seasons studied.

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