Multiple contributory factors to the age distribution of disease cases: a modeling study in the context of influenza A(H3N2v)

Clin Infect Dis. 2013 Jul;57 Suppl 1(Suppl 1):S23-7. doi: 10.1093/cid/cit298.

Abstract

Background: In late 2011 and early 2012, 13 cases of human influenza resulted from infection with a novel triple reassortant swine-origin influenza virus, influenza A (H3N2) variant. This variant was notable for its inclusion of the matrix gene from the 2009 influenza A(H1N1) pandemic virus. While most of these confirmed cases were among children, the transmission potential and likely age-dependent susceptibility to the virus was unknown. Preliminary serologic studies indicated that very young children have less protection than older children and adults.

Methods: We construct a mathematical transmission model of influenza transmission that allows for external zoonotic exposure to infection and show how exposure and susceptibility-related factors contribute to the observed case distribution.

Results and conclusions: Age-dependent susceptibility to infection strongly influences epidemic dynamics. The result is that the risk of an outbreak in a highly susceptible age group may be substantially higher than in an older age group with less susceptibility, but exposure-related factors must also be accounted for when interpreting case data.

Keywords: emerging infection; modeling; novel influenza; zoonosis.

Publication types

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

MeSH terms

  • Adolescent
  • Adult
  • Age Distribution
  • Age Factors
  • Aged
  • Aged, 80 and over
  • Animals
  • Child
  • Child, Preschool
  • Disease Outbreaks*
  • Humans
  • Infant
  • Influenza A Virus, H1N1 Subtype / genetics
  • Influenza A Virus, H3N2 Subtype / genetics
  • Influenza A Virus, H3N2 Subtype / isolation & purification*
  • Influenza, Human / epidemiology*
  • Influenza, Human / transmission
  • Influenza, Human / virology
  • Middle Aged
  • Models, Theoretical
  • Orthomyxoviridae Infections / transmission
  • Orthomyxoviridae Infections / veterinary
  • Orthomyxoviridae Infections / virology
  • Swine
  • Swine Diseases / transmission
  • Swine Diseases / virology
  • United States / epidemiology
  • Young Adult