title: Deaths averted by influenza vaccination in the U.S. during the seasons 2005/06 through 2013/14.
abstract: BACKGROUND
  Excess mortality due to seasonal influenza is substantial, yet quantitative estimates of the benefit of annual vaccination programs on influenza-associated mortality are lacking.
  
  
  METHODS
  We estimated the numbers of deaths averted by vaccination in four age groups (0.5 to 4, 5 to 19, 20 to 64 and ≥65 yrs.) for the nine influenza seasons from 2005/6 through 2013/14. These estimates were obtained using a Monte Carlo approach applied to weekly U.S. age group-specific estimates of influenza-associated excess mortality, monthly vaccination coverage estimates and summary seasonal influenza vaccine effectiveness estimates to obtain estimates of the number of deaths averted by vaccination. The estimates are conservative as they do not include indirect vaccination effects.
  
  
  RESULTS
  From August, 2005 through June, 2014, we estimated that 40,127 (95% confidence interval [CI] 25,694 to 59,210) deaths were averted by influenza vaccination. We found that of all studied seasons the most deaths were averted by influenza vaccination during the 2012/13 season (9398; 95% CI 2,386 to 19,897) and the fewest during the 2009/10 pandemic (222; 95% CI 79 to 347). Of all influenza-associated deaths averted, 88.9% (95% CI 83 to 92.5%) were in people ≥65 yrs. old.
  
  
  CONCLUSIONS
  The estimated number of deaths averted by the US annual influenza vaccination program is considerable, especially among elderly adults and even when vaccine effectiveness is modest, such as in the 2012/13 season. As indirect effects ("herd immunity") of vaccination are ignored, these estimates represent lower bound estimates and are thus conservative given valid excess mortality estimates.
authors: Influenza Division, Centers for Disease Control and Prevention, 1600 Clifton Road NE, MS A-20, Atlanta, 30333 GA, USA; Battelle Memorial Institute, Atlanta, GA, USA. Electronic address: vor1@cdc.gov.
authors: Ivo M
authors: IM
authors: Foppa
authors: Influenza Division, Centers for Disease Control and Prevention, 1600 Clifton Road NE, MS A-20, Atlanta, 30333 GA, USA; Battelle Memorial Institute, Atlanta, GA, USA.
authors: Po-Yung
authors: PY
authors: Cheng
authors: Influenza Division, Centers for Disease Control and Prevention, 1600 Clifton Road NE, MS A-20, Atlanta, 30333 GA, USA; Atlanta Research and Education Foundation, GA, USA.
authors: Sue B
authors: SB
authors: Reynolds
authors: Influenza Division, Centers for Disease Control and Prevention, 1600 Clifton Road NE, MS A-20, Atlanta, 30333 GA, USA.
authors: David K
authors: DK
authors: Shay
authors: National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA; IHRC.Inc, Atlanta, GA, USA.
authors: Cristina
authors: C
authors: Carias
authors: Influenza Division, Centers for Disease Control and Prevention, 1600 Clifton Road NE, MS A-20, Atlanta, 30333 GA, USA.
authors: Joseph S
authors: JS
authors: Bresee
authors: Influenza Division, Centers for Disease Control and Prevention, 1600 Clifton Road NE, MS A-20, Atlanta, 30333 GA, USA; Battelle Memorial Institute, Atlanta, GA, USA.
authors: Inkyu K
authors: IK
authors: Kim
authors: National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors: Manoj
authors: M
authors: Gambhir
authors: Influenza Division, Centers for Disease Control and Prevention, 1600 Clifton Road NE, MS A-20, Atlanta, 30333 GA, USA.
authors: Alicia M
authors: AM
authors: Fry
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001499:Bayes Theorem; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D017589:Immunization Programs; D007223:Infant; D007252:Influenza Vaccines / Q000008:administration & dosage; D007251:Influenza, Human / Q000401:mortality* / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D012621:Seasons; D013997:Time Factors; D014481:United States; D014611:Vaccination / Q000706:statistics & numerical data*; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines
keywords: Averted deaths; Bayesian analysis; Influenza; Influenza vaccine; Influenza-associated mortality; Monte Carlo simulation