The current flu Vaccine appear to be a bad match for the dominant strain so far this influenza season, new research suggests, leading experts to warn that the United States could be in for a bad flu season, on top of what’s already shaping up to be another devastating surge of Covid cases.
Before each flu season, scientists must predict which strains will be the most common, and design a flu shot to match these predictions. This year’s flu shot includes four strains. The version of the H3N2 strain of influenza, is turning out to be a bad match for the version of H3N2, called 2a2, that’s in wide circulation in the U.S.
Hensley’s study was posted Wednesday to a preprint server, meaning it has not yet been peer-reviewed. The H3N2 strain makes up for at least 99 percent of all flu cases in the U.S., according to the Centers for Disease Control and Prevention, though the agency does not specify how many of those cases are caused by the 2a2 version of the strain.
The presence of the 2a2 version means the Vaccine may not protect as well against infection, because it’s not the version included in the Vaccine, Hensley said. The flu shot is never a perfect match for the influenza viruses that end up in wide circulation, but even so, the Vaccine still reduces a person’s risk of severe illness from the flu.