title: Influenza Vaccine Effectiveness Against 2009 Pandemic Influenza A(H1N1) Virus Differed by Vaccine Type During 2013-2014 in the United States.
abstract: BACKGROUND
  The predominant strain during the 2013-2014 influenza season was 2009 pandemic influenza A(H1N1) virus (A[H1N1]pdm09). This vaccine-component has remained unchanged from 2009.
  
  
  METHODS
  The US Flu Vaccine Effectiveness Network enrolled subjects aged ≥6 months with medically attended acute respiratory illness (MAARI), including cough, with illness onset ≤7 days before enrollment. Influenza was confirmed by reverse-transcription polymerase chain reaction (RT-PCR). We determined the effectiveness of trivalent or quadrivalent inactivated influenza vaccine (IIV) among subjects ages ≥6 months and the effectiveness of quadrivalent live attenuated influenza vaccine (LAIV4) among children aged 2-17 years, using a test-negative design. The effect of prior receipt of any A(H1N1)pdm09-containing vaccine since 2009 on the effectiveness of current-season vaccine was assessed.
  
  
  RESULTS
  We enrolled 5999 subjects; 5637 (94%) were analyzed; 18% had RT-PCR-confirmed A(H1N1)pdm09-related MAARI. Overall, the effectiveness of vaccine against A(H1N1)pdm09-related MAARI was 54% (95% confidence interval [CI], 46%-61%). Among fully vaccinated children aged 2-17 years, the effectiveness of LAIV4 was 17% (95% CI, -39% to 51%) and the effectiveness of IIV was 60% (95% CI, 36%-74%). Subjects aged ≥9 years showed significant residual protection of any prior A(H1N1)pdm09-containing vaccine dose(s) received since 2009, as did children <9 years old considered fully vaccinated by prior season.
  
  
  CONCLUSIONS
  During 2013-2014, IIV was significantly effective against A(H1N1)pdm09. Lack of LAIV4 effectiveness in children highlights the importance of continued annual monitoring of effectiveness of influenza vaccines in the United States.
authors.affiliation: Baylor Scott & White Health, Texas A&M Health Science Center College of Medicine, Temple.
authors.forename: Manjusha
authors.initials: M
authors.lastname: Gaglani
authors.affiliation: Baylor Scott & White Health, Texas A&M Health Science Center College of Medicine, Temple.
authors.forename: Jessica
authors.initials: J
authors.lastname: Pruszynski
authors.affiliation: Baylor Scott & White Health, Texas A&M Health Science Center College of Medicine, Temple.
authors.forename: Kempapura
authors.initials: K
authors.lastname: Murthy
authors.affiliation: Baylor Scott & White Health, Texas A&M Health Science Center College of Medicine, Temple.
authors.forename: Lydia
authors.initials: L
authors.lastname: Clipper
authors.affiliation: Baylor Scott & White Health, Texas A&M Health Science Center College of Medicine, Temple.
authors.forename: Anne
authors.initials: A
authors.lastname: Robertson
authors.affiliation: Baylor Scott & White Health, Texas A&M Health Science Center College of Medicine, Temple.
authors.forename: Michael
authors.initials: M
authors.lastname: Reis
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Jessie R
authors.initials: JR
authors.lastname: Chung
authors.affiliation: Baylor College of Medicine, Houston, Texas.
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Piedra
authors.affiliation: Baylor College of Medicine, Houston, Texas.
authors.forename: Vasanthi
authors.initials: V
authors.lastname: Avadhanula
authors.affiliation: University of Pittsburgh, Pennsylvania.
authors.forename: Mary Patricia
authors.initials: MP
authors.lastname: Nowalk
authors.affiliation: University of Pittsburgh, Pennsylvania.
authors.forename: Richard K
authors.initials: RK
authors.lastname: Zimmerman
authors.affiliation: Group Health Research Institute, Seattle, Washington.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Jackson
authors.affiliation: Group Health Research Institute, Seattle, Washington.
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Jackson
authors.affiliation: Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor.
authors.forename: Joshua G
authors.initials: JG
authors.lastname: Petrie
authors.affiliation: Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor.
authors.forename: Suzanne E
authors.initials: SE
authors.lastname: Ohmit
authors.affiliation: Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor.
authors.forename: Arnold S
authors.initials: AS
authors.lastname: Monto
authors.affiliation: Marshfield Clinic Research Foundation, Wisconsin.
authors.forename: Huong Q
authors.initials: HQ
authors.lastname: McLean
authors.affiliation: Marshfield Clinic Research Foundation, Wisconsin.
authors.forename: Edward A
authors.initials: EA
authors.lastname: Belongia
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Alicia M
authors.initials: AM
authors.lastname: Fry
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Brendan
authors.initials: B
authors.lastname: Flannery
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D007252:Influenza Vaccines; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control* / Q000821:virology; D008297:Male; D008875:Middle Aged; D058873:Pandemics / Q000517:prevention & control*; D012621:Seasons; D014481:United States / Q000453:epidemiology; D014611:Vaccination; D015164:Vaccines, Inactivated; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines; D015164:Vaccines, Inactivated
keywords: influenza; influenza vaccine; influenza vaccine effectiveness; vaccine effectiveness