Have you been vaccinated? Think again!

2009 WA influenza epidemic overview

Last year the Southern Hemisphere was first to experience a full influenza season prior to the introduction of an effective vaccine. This gave us an opportunity to tackle some important questions about epidemic influenza and how it compared with seasonal infection.

WHO has kept us upto date on the global picture.

In Western Australia the main source was ex-Victoria where the epidemic took hold a few weeks earlier. The detailed series of situation reports can be found on the DoHA website. The first WA case was on 24th May. Features of systemic infection were more common in those with epidemic influenza.

  • It affected a younger age group than seasonal influenza, notably including pregnant women.
  • There was no obvious impact on mortality, but detailed figures have yet to appear.
  • School closures were unsuccessful in preventing transmission.
  • There was household transmission with a mean serial interval of over 3 days.
  • Reproduction number was 1.2-1.4
  • A substantial proportion of hospital admissions for influenza ended up in intensive care, more than half of whom were < 40 years of age
  • The CURB score was a poor predictor of pneumonia
  • Upper respiratory samples had poor sensitivity compared to lower respiratory samples
  • Oseltamivir resistance has been reported but hasn’t yet been associated with further transmission
  • H1N1 2009 is predicted to be the dominant influenza virus of 2010
  • Vaccine coverage stands at only 15-20%

μGnome is grateful to David Smith, Gary Dowse & David Speers for these insights and looks forward to more details before the next influenza season.



  1. nice post. thanks.

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