Repeated influenza vaccination of healthy children and adults: borrow now, pay later?

Epidemiol Infect. 2006 Feb;134(1):63-70. doi: 10.1017/S0950268805005479.


A growing number of publications are recommending annual influenza vaccination of healthy children and adults. However, the long-term consequences of repeated influenza vaccination are unknown. We used a simple model of recurrent influenza infection to assess the likely impact of various repeated influenza vaccination scenarios. The model was based on a Markovian framework and was fitted on annual incidence rates of influenza infection by age. We found that natural influenza infection reduced the risk of being re-infected by 15.4% (95% confidence interval 7.1-23.0). Various scenarios of repeated influenza vaccination were then simulated and compared with a reference scenario where vaccination is given from age 65 years onwards. We show that repeated vaccination at a young age substantially increases the risk of influenza in older age, by a factor ranging between 1.2 (vaccination after 50 years) to 2.4 (vaccination from birth). These findings have important implications for influenza vaccination policies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Child
  • Child, Preschool
  • Female
  • Humans
  • Immunization Schedule
  • Incidence
  • Infant
  • Infant, Newborn
  • Influenza Vaccines / administration & dosage*
  • Influenza, Human / prevention & control*
  • Male
  • Markov Chains
  • Middle Aged
  • Models, Theoretical*
  • Recurrence
  • Risk Factors


  • Influenza Vaccines