Influenza vaccine effectiveness in preventing laboratory-confirmed influenza in outpatient settings: A test-negative case-control study in Beijing, China, 2016/17 season

Our study suggested a moderate VE against influenza A(H1N1)pdm09, but low VE against influenza A(H3N2) in Beijing, 2016/17 season. Amino acid substitutions in the hemagglutinin may contribute to the low VE against influenza A(H3N2) for this season.