Intensive Care Admissions and Associated Severity of Influenza B Versus A During Influenza B Vaccine–mismatched Seasons

: Patients admitted to hospital with influenza B and A in Jerusalem, Israel, during the 2015-2016 and 2017-2018 influenza seasons demonstrated similar rates of intensive care unit (ICU) admission and associated disease severity. Most (63%) influenza B ICU patients received influenza B-mismatched trivalent vaccine. These findings call into question the equivalence of trivalent and quadrivalent vaccines in preventing severe influenza B.