Epidemiology of the 2012 influenza season in Victoria, Australia

Western Pac Surveill Response J. 2013 Aug 23;4(3):42-50. doi: 10.5365/WPSAR.2013.4.2.007. eCollection 2013 Jul-Sep.

Abstract

Objective: To assess the magnitude and severity of the 2012 influenza season in Victoria, Australia using surveillance data from five sources.

Methods: Data from influenza notifications, sentinel general practices, a sentinel hospital network, a sentinel locum service and strain typing databases for 2012 were descriptively analysed.

Results: Influenza and influenza-like illness activity was moderate compared to previous years, although a considerable increase in notified laboratory-confirmed influenza was observed. Type A influenza comprised between 83% and 87% of cases from the general practitioners, hospitals and notifiable surveillance data. Influenza A/H3 was dominant in July and August, and most tested isolates were antigenically similar to the A/Perth/16/2009 virus used in the vaccine. There was a smaller peak of influenza type B in September. No tested viruses were resistant to any neuraminidase inhibitor antivirals. Higher proportions of type A/H3, hospitalized cases and those with a comorbid condition indicated for influenza vaccination were aged 65 years or older. Influenza vaccination coverage among influenza-like illness patients was 24% in sentinel general practices and 50% in hospitals.

Discussion: The 2012 influenza season in Victoria was average compared to previous years, with an increased dominance of A/H3 accompanied by increases in older and hospitalized cases. Differences in magnitude and the epidemiological profile of cases detected by the different data sources demonstrate the importance of using a range of surveillance data to assess the relative severity of influenza seasons.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Child
  • Child, Preschool
  • Communicable Disease Control
  • Disease Notification / statistics & numerical data
  • Disease Outbreaks / statistics & numerical data*
  • Female
  • Humans
  • Infant
  • Infant, Newborn
  • Influenza A virus / isolation & purification*
  • Influenza B virus / isolation & purification*
  • Influenza Vaccines / administration & dosage
  • Influenza, Human / diagnosis*
  • Influenza, Human / epidemiology*
  • Influenza, Human / prevention & control
  • Male
  • Middle Aged
  • Population Surveillance*
  • Seasons
  • Vaccination
  • Victoria / epidemiology

Substances

  • Influenza Vaccines