Pandemic potential of influenza A H1N1 justifies warnings
11 May 2009
A swine flu study led by Professor Neil Ferguson of the MRC Centre for Outbreak Analysis and Modelling at Imperial College London concludes that the swine flu-like influenza A (H1N1) virus’ potential to spread justified the World Health Organization (WHO) decision to raise the global pandemic alert to level 5 on 29 April 2009.
Professor Ferguson and colleagues analysed the Mexican outbreak using early data on international spread and viral and genetic diversity to make an early assessment of the virus’ severity and potential to spread. The study has found that transmissibility is higher than that of seasonal flu.
As more detailed information about spread in schools and households is gathered a more informative estimate of outbreak patterns will be possible.
While the WHO is reporting about 4,700 confirmed cases in 30 countries, the new analysis estimates there were between 6,000 and 32,000 cases in Mexico by late April 2009. Information about the number of confirmed and suspected deaths from the virus was combined with the number of cases to give an estimated fatality ratio of 0.4%.
Professor Ferguson of Imperial College, London, has said that the early analysis suggests the outbreak is going to be comparable to that of 20th century pandemics but that it's difficult to quantify the human health impact at this stage.
Original research paper: Pandemic potential of a novel strain of influenza A (H1N1): Early findings is published online in Science Express today (11 May 2009)
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