Blame the Flu Epidemic on a Weak Vaccine
This season’s shot is struggling to protect against a resilient strain that’s killed thousands of Americans. A new CDC report explains why.
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It turns out the rumors were true: This year’s flu shot is indeed less effective than usual.
An unusually resilient strain of influenza called H3N2 has been the predominant assailant this season, and the vaccine rolled out last year was ill-suited to protect against it. While previous analyses from Canada and Australia on its H3N2 effectiveness lent some non-significant support to suspicions about the shot, a new report from the Centers for Disease Control and Prevention laid doubt to rest: This season’s vaccine reduced illness caused by H3N2 by only 25 percent.