health & wellness

This Season's Flu Vaccine Was Poor Match for the Virus, CDC Reports

But for the second year in a row, flu cases have remained abnormally low, staving off fears of a "twindemic"

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This season's flu vaccine offers meager protection against mild cases of influenza, the Centers for Disease Control and Prevention reported Thursday.

Against the most common flu strain circulating this season, the flu shot reduced a person's chance of getting a mild case by 16 percent, which is "considered not statistically significant," the CDC authors wrote, though the shots should offer some protection against more severe illness.

Put more bluntly, the flu vaccine was “essentially ineffective,” said Dr. William Schaffner, an infectious diseases expert at the Vanderbilt University Medical Center.

Indeed, research from earlier in the flu season found that the vaccine was a poor match for the H3N2 strain of the virus. That study, from researchers at the University of Pennsylvania, was posted as a pre-print, meaning it had not been peer-reviewed.

Thursday's CDC report confirmed that the dominant strain detected this season was H3N2 — a strain that flu experts say is particularly troublesome, as it tends to mutate faster than other variants of influenza and traditionally leads to more hospitalizations and deaths.

The findings come amid the nation's second flu season in a row with low flu activity overall. Flu cases did start to rise in the fall, sparking fears of a "twindemic" of Covid-19 and the flu, but cases never took off like they do in typical flu seasons.

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