Early CDC Data Suggest This Season’s Flu Vaccine May Have Been Poor Match To Common Virus Strain

CBS News (2/25, Tin) reports early CDC data suggest “this season’s influenza vaccine may have been a poor match to a strain of the flu virus that caused many infections this winter.” As many as “910,000 hospitalizations are estimated to have been caused by the flu since October 2024, which puts the season on track to be the most severe in at least a decade.” Many of the flu viruses that the CDC tested this season were “well-recognized” by antibodies targeted to the vaccine. But “against the H3N2 strain of influenza, which this season has made up just over half of the influenza A viruses scrutinized by the agency, only around 50.9% of the samples were ‘well-recognized’ by the antibodies.” This is significantly lower compared to this time last year, “when the CDC reported that all H3N2 viruses they tested were ‘well-recognized’ by the vaccine virus antibodies.”