Childhood Influenza

Number Needed to Vaccinate to Prevent 1 Hospitalization or Outpatient Visit

This article describes efforts to use information on influenza burden and vaccine efficacy to estimate how influenza vaccine recommendations might impact children's influenza-related hospitalizations and outpatient visits. Researchers reviewed studies that provided information as to rates of vaccination per 1,000 children ages 6 to 23 months and 24 to 59 months. Vaccine efficacy was measured in 25 percent, 50 percent and 75 percent markers of how much vaccines corresponded with active strains of influenza.

Key Findings:

  • In order to avoid one influenza-related hospitalization, vaccinations would need to be given to an estimated 1,031 to 3,050 children ages 6 to 23 months and 4,255 to 6,897 children ages 24 to 59 months.
  • The amount of children requiring influenza vaccination to avoid hospitalization decreased as vaccine efficacy and severity of influenza season increased.
  • The amount of children that would require vaccination to avoid influenza-related hospitalization was estimated to be between 45-fold to more than 100-fold greater than the number required to be vaccinated to avoid an influenza-related outpatient visit.
  • In order to avoid one influenza-related outpatient visit, vaccinations (with 50% vaccine efficacy) would need to be given to an estimated 12 to 42 children ages 6 to 59 months.