Seasonal influenza vaccine effectiveness in pre- and full-term children aged 6-23 months over multiple seasons

Vaccine. 2013 Jun 24;31(29):2974-8. doi: 10.1016/j.vaccine.2013.05.011. Epub 2013 May 18.

Abstract

Introduction: This study aimed to determine the effectiveness of seasonal influenza vaccine in pre- and full-term children aged 6-23 months.

Methods: We examined a cohort of 683,354 young children (7.7% preterm) over five influenza seasons (2004-2005 to 2008-2009) in Ontario, Canada. Vaccine effectiveness was estimated using influenza-coded ambulatory visits during virologically-confirmed influenza season periods as the outcome and multivariable Cox proportional hazards modeling.

Results: Full vaccination was associated with a 19% reduction in influenza-coded ambulatory visits (HR=0.81; 95% CI, 0.68-0.97) in all children, and an 18% reduction in full-term children (HR=0.82; 95% CI, 0.68-0.99). We did not find significant vaccine effectiveness for preterm children. No benefit was found for partial vaccination.

Conclusions: In children younger than two years, only full influenza vaccination is associated with reduced influenza-coded ambulatory visits. Since the effectiveness of influenza vaccination in preterm children remains uncertain, further study of this highly vulnerable population is warranted.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ambulatory Care / statistics & numerical data
  • Cohort Studies
  • Female
  • Humans
  • Infant
  • Infant, Newborn
  • Infant, Premature*
  • Influenza Vaccines / administration & dosage
  • Influenza Vaccines / immunology*
  • Influenza, Human / epidemiology*
  • Influenza, Human / immunology
  • Influenza, Human / prevention & control*
  • Male
  • Ontario / epidemiology
  • Seasons
  • Vaccination

Substances

  • Influenza Vaccines