Flu Vaccines Poor Match to Influenza Strains This Season

According to the Centers for Disease Control and Prevention (CDC), this season’s influenza (flu) vaccines offered meager protection against mild cases of influenza. Against the most common flu strain circulating this season, the flu vaccines reduced a person’s chance of getting a mild case by 16 percent, which is “considered not statistically significant,” although the vaccines should offer some protection against more severe illness. Put more bluntly, the flu vaccine was “essentially ineffective,” said William Schaffner, MD, an infectious diseases expert at the Vanderbilt University Medical Center.

Research from earlier in the flu season found the vaccine was a poor match for the H3N2 strain of the virus, which CDC confirmed is the dominant strain detected this season. That flu strain, experts say, is particularly troublesome since it tends to mutate faster than other variants of influenza and traditionally leads to more hospitalizations and deaths.

These 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.