There is so little detailed analysis of the way in which pandemics spread – so much of the current thinking is based on opinion and presumption
- Julia Gog
The most detailed analysis to date of the spread of the H1N1 2009 pandemic influenza virus, known informally as ‘swine flu’, has found that short-range travel was likely the primary driver for the 2009 pandemic in the United States, in contrast with popularly accepted views on the way diseases spread.
The study, based on data gathered from health insurance claims made throughout 2009, found that international air travel, which was previously thought to be important in the pandemic, played only a minor role in its spread within the US.
A team of researchers from University of Cambridge and the US, including Princeton University and National Institutes of Health, analysed data from 271 American cities and their surrounding suburban areas, covering 90% of the population of the 48 contiguous states.
The data were used to test mathematical models to pinpoint the role and importance of factors associated with H1N1’s arrival and spread, including demographics, school opening dates, humidity levels and immunity from previous outbreaks.
According to this new analysis, school-age children accelerated the spread of the pandemic, which was transmitted over short distances, in contrast with widespread reports at the time linking the pandemic to international air travel and population density. The results are published in the journal PLOS Computational Biology.
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Image:Map of the H1N1 influenza pandemic in 2009. The size of the dots is relative to city size, and the colours relate to the number of influenza cases, with green the lowest and purple the highest.
Credit: Julia Gog
Reproduced courtesy of the University of Cambridge
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