London School of Hygiene & Tropical Medicine

The continuing cold snap which has closed schools across the country and caused chaos on the roads could have one upside – it may well delay this year’s flu epidemic until next Spring.

Last year, an online flu surveillance site, www.flusurvey.org.uk, found that people exhibited holiday-like behaviour during the heavy snow and the number of people each person contacted dropped dramatically. This in turn could affect the transmission of influenza and delay the start of an annual epidemic.

Professor John Edmunds of the London School of Hygiene & Tropical Medicine, which set up the flusurvey, says: 'School holidays have a huge impact on flu epidemics, and the snow at the beginning of 2010 created the effect of an extra holiday. If we see a repeat of that this year, then the flu epidemic could be delayed until February or March 2011'.

Scientists at the flusurvey asked people to report their social contacts during the flu season. His colleague Ellen Brooks-Pollock, a Research Fellow in Mathematical Modelling at the School, explains: 'We measured the drop in people’s social contacts during the snowy period by accident, because it occurred when we usually observe flu epidemics'. The data collected by the flusurvey can then be incorporated into mathematical models to predict the impact of a coming epidemic.

'Of course, we don’t know the biological details of the coming flu epidemic. What we do know is that if the epidemic is similar to some previous years, this cold snap could delay the peak of a flu epidemic by several weeks'.

To interview John Edmunds or Ellen Brooks-Pollock, or for further information, please contact the London School of Hygiene & Tropical Medicine Press Office on 00 44 (0) 207 2073 or email lindsay.wright@lshtm.ac.uk

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