The Household Influenza Vaccine Effectiveness Study: Lack of Antibody Response and Protection Following Receipt of 2014–2015 Influenza Vaccine

Background Antigenically drifted A(H3N2) viruses circulated extensively during the 2014–2015 influenza season. Vaccine effectiveness (VE) was low and not significant among outpatients but in a hospitalized population was 43%. At least one study paradoxically observed increased A(H3N2) infection among those vaccinated 3 consecutive years.