The flu vaccine engineered for 2022-'23's atypical early season reduced the risk of "medically attended influenza A(H3N2) illness" by half, according to a study published Feb. 2 in Eurosurveillance.
In a Canadian study evaluating the influenza vaccine's effectiveness, researchers said this efficacy estimate is higher than what's normally reported. To study vaccine efficacy, they tested for influenza among 1,490 patients who had influenza-like-illness across Alberta, British Columbia, Ontario and Quebec.
"Shorter time since vaccination and/or better match with the updated vaccine may have improved [vaccine effectiveness]," the researchers concluded. "The extent to which relative pause in influenza virus circulation during the coronavirus disease (COVID-19) pandemic may have affected the current VE estimates, is uncertain."