Influenza vaccine effectiveness in households with children during the 2012-2013 season: assessments of prior vaccination and serologic susceptibility

J Infect Dis. 2015 May 15;211(10):1519-28. doi: 10.1093/infdis/jiu650. Epub 2014 Nov 21.


Background: There are recognized needs to identify determinants of influenza vaccine effectiveness (VE), including the effect of repeated annual vaccination.

Methods: We recruited 321 households with 1426 members, including 833 children, and followed them during the 2012-2013 influenza season; specimens were collected from subjects with reported acute respiratory illnesses. We estimated the effectiveness of documented influenza vaccination in preventing laboratory-confirmed influenza, using adjusted Cox proportional hazards models. Antibody titers in a subset of subjects were determined by a hemagglutination inhibition assay to determine the subjects' preseason susceptibility to influenza.

Results: Influenza was identified in 76 (24%) households and 111 (8%) individuals. VE point estimates indicated significant protection in adults (48%; 95% confidence interval [CI], 1%-72%), similar protection in children aged 9-17 years (49%; 95% CI, -16% to 78%), but no evidence of effectiveness in children aged <9 years (-4%; 95% CI, -110% to 49%). Lower VE was observed in those vaccinated in both the current and prior seasons, compared with those vaccinated in the current season only; susceptibility titers against type A but not type B were consistent with this observation. Residual protection from vaccination in the prior season was indicated by both VE and serologic results.

Conclusions: Prior vaccination appears to modify VE by both residual protection and reduced vaccine response.

Keywords: households with children; influenza; serologic susceptibility; vaccine effectiveness.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Antibodies, Viral / blood*
  • Child
  • Family Characteristics
  • Female
  • Hemagglutination Inhibition Tests
  • Humans
  • Infant
  • Influenza Vaccines / administration & dosage*
  • Influenza Vaccines / immunology*
  • Influenza, Human / immunology*
  • Influenza, Human / prevention & control*
  • Male
  • Middle Aged
  • Treatment Outcome
  • Young Adult


  • Antibodies, Viral
  • Influenza Vaccines