biostudies-literatureFlannery BUniversity of MichiganKaiser Permanente Washington Research InstituteNCATS NIH HHSUniversity of PittsburghMarshfield Clinic Research InstituteBaylor Scott and White HealthcareNational Institutes of HealthNCIRD CDC HHS1798-1806https://www.ebi.ac.uk/biostudies/studies/S-EPMC6522684biostudies-literatureUnknown68(11)<h4>Background</h4>In recent influenza seasons, the effectiveness of inactivated influenza vaccines against circulating A(H3N2) virus has been lower than against A(H1N1)pdm09 and B viruses, even when circulating viruses remained antigenically similar to vaccine components.<h4>Methods</h4>During the 2016-2017 influenza season, vaccine effectiveness (VE) across age groups and vaccine types was examined among outpatients with acute respiratory illness at 5 US sites using a test-negative design that compared the odds of vaccination among reverse transcription polymerase chain reaction-confirmed influenza positives and negatives.<h4>Results</h4>Among 7083 enrollees, 1342 (19%) tested positive for influenza A(H3N2), 648 (9%) were positive for influenza B (including B/Yamagata, n = 577), and 5040 (71%) were influenza negative. Vaccine effectiveness was 40% (95% confidence interval [CI], 32% to 46%) against any influenza virus, 33% (95% CI, 23% to 41%) against influenza A(H3N2) viruses, and 53% (95% CI, 43% to 61%) against influenza B viruses.<h4>Conclusions</h4>The 2016-2017 influenza vaccines provided moderate protection against any influenza among outpatients but were less protective against influenza A(H3N2) viruses than B viruses. Approaches to improving effectiveness against A(H3N2) viruses are needed.Clinical infectious diseases : an official publication of the Infectious Diseases Society of AmericaInfluenza Vaccine Effectiveness in the United States During the 2016-2017 Season.PMC6522684U01 IP001039U01 IP001037U01 IP001038U01 IP001035U01 IP0010341U01 IP0010341U01 IP0010351U01 IP001038UL1TR0018571U01 IP001039UL1 TR0018571U01 IP001037Jackson LAChung JRMurthy KMcLean HQZimmerman RKMartin ETGaglani MRolfes MAFry AMJackson MLBelongia EAMonto ASNowalk MPUS Flu VE InvestigatorsSpencer SFlannery BfalseInfluenza Vaccine Effectiveness in the United States During the 2016-2017 Season.<h4>Background</h4>In recent influenza seasons, the effectiveness of inactivated influenza vaccines against circulating A(H3N2) virus has been lower than against A(H1N1)pdm09 and B viruses, even when circulating viruses remained antigenically similar to vaccine components.<h4>Methods</h4>During the 2016-2017 influenza season, vaccine effectiveness (VE) across age groups and vaccine types was examined among outpatients with acute respiratory illness at 5 US sites using a test-negative design that compared the odds of vaccination among reverse transcription polymerase chain reaction-confirmed influenza positives and negatives.<h4>Results</h4>Among 7083 enrollees, 1342 (19%) tested positive for influenza A(H3N2), 648 (9%) were positive for influenza B (including B/Yamagata, n = 577), and 5040 (71%) were influenza negative. Vaccine effectiveness was 40% (95% confidence interval [CI], 32% to 46%) against any influenza virus, 33% (95% CI, 23% to 41%) against influenza A(H3N2) viruses, and 53% (95% CI, 43% to 61%) against influenza B viruses.<h4>Conclusions</h4>The 2016-2017 influenza vaccines provided moderate protection against any influenza among outpatients but were less protective against influenza A(H3N2) viruses than B viruses. Approaches to improving effectiveness against A(H3N2) viruses are needed.2019-01-01T00:00:00Z2019 May2025-04-04T18:36:38.416Z2019-09-14T07:03:00ZS-EPMC65226843020485410.1093/cid/ciy775