Earliest infections predict the age distribution of seasonal influenza A cases

Elife. 2020 Jul 7:9:e50060. doi: 10.7554/eLife.50060.

Abstract

Seasonal variation in the age distribution of influenza A cases suggests that factors other than age shape susceptibility to medically attended infection. We ask whether these differences can be partly explained by protection conferred by childhood influenza infection, which has lasting impacts on immune responses to influenza and protection against new influenza A subtypes (phenomena known as original antigenic sin and immune imprinting). Fitting a statistical model to data from studies of influenza vaccine effectiveness (VE), we find that primary infection appears to reduce the risk of medically attended infection with that subtype throughout life. This effect is stronger for H1N1 compared to H3N2. Additionally, we find evidence that VE varies with both age and birth year, suggesting that VE is sensitive to early exposures. Our findings may improve estimates of age-specific risk and VE in similarly vaccinated populations and thus improve forecasting and vaccination strategies to combat seasonal influenza.

Keywords: epidemiology; global health; human; imprinting; infectious disease; influenza; microbiology; original antigenic sin; vaccine effectiveness; virus.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adolescent
  • Adult
  • Age Distribution*
  • Age Factors
  • Aged
  • Aged, 80 and over
  • Case-Control Studies
  • Child
  • Child, Preschool
  • Cohort Studies
  • Humans
  • Incidence
  • Infant
  • Influenza A Virus, H1N1 Subtype / immunology
  • Influenza A Virus, H1N1 Subtype / physiology*
  • Influenza A Virus, H3N2 Subtype / immunology
  • Influenza A Virus, H3N2 Subtype / physiology*
  • Influenza Vaccines / administration & dosage*
  • Influenza, Human / epidemiology*
  • Influenza, Human / virology
  • Middle Aged
  • Models, Theoretical
  • Prevalence
  • Seasons
  • Vaccination / statistics & numerical data*
  • Wisconsin / epidemiology
  • Young Adult

Substances

  • Influenza Vaccines