Friday, 1 May 2009

Research from The University of Western Australia will give vital clues to public health authorities in dealing with potential pandemics such as the current "swine flu" (H1N1) outbreak.

The research, published in the journal BMC Public Health this week, found imposing "social distancing" measures such as school closures, home isolation, partial closure of workplaces and reduced community contact, if done rapidly, could prevent a local epidemic.

"The timing of activation of such non-pharmaceutical interventions is critical," said Professor George Milne, who along with Dr Joel Kelso and Dr Simon Huband used a computer simulation model to emulate the spread of influenza (in this case, H5N1 "avian" influenza, but the results are directly applicable to H1N1).

"For a very transmissible strain, application of all four interventions at the same time as the first case is introduced, and enforcing these draconian measures continuously, can potentially hold the illness rate at 16 per cent (compared to 73 per cent if they are not used)."

The research assumed 100% of infectious children and 90% adults are home quarantined and a 50% reduction in workplace attendance and community-wide contact.

The model used statistical data about the population of Albany, a town of 30,000 people in south-west Western Australia.

Developed by the team from UWA's School of Computer Science and Software Engineering, the model is believed to be the most detailed replication of an actual community - down to individual schools, employers and the exact make-up of households - to be used to quantify the impact of alternative intervention strategies.

Professor Milne said the model showed that non-pharmaceutical social distancing interventions could reduce the rate of development and the overall burden of epidemics.

"While such draconian measures will only be mandated under extreme circumstances, given their impact on personal freedom, they appear to play a key role in delaying the development of a ‘worst case' influenza epidemic," he said. "Social distancing may be critical in holding back an epidemic until vaccines are deployed on a sufficient scale that subsequent relaxation of these measures won't result in an acceleration of the outbreak."

"The measures must be employed as soon as possible if they are to have maximum effect. We found that for an outbreak as infectious as the 1918 Spanish Flu pandemic, a combination of all intervention measures must be introduced within two weeks of the first case appearing in a town or city to prevent an epidemic developing. Delays of two, three and four weeks resulted in final attack rates of seven per cent, 21 per cent and 45 per cent respectively."

The UWA team has provided reports based on their two published papers to the Commonwealth Department of Health and Ageing (DoHA) and the World Health Organisation (WHO) and received funding from the National Health and Medical Research Council, DoHA and WHO.

For copies of the article, see

Media references

Professor George Milne (+61 8)  6488 2717  /  (+61 4) 17 820 768
Dr Joel Kelso (+61 8)  6488 1536
Janine MacDonald (UWA Public Affairs)  (+61 8)  6488 5563  /  (+61 4) 32 637 716


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