Researchers studying the H1N1 Swine Flu virus, which killed more than 18,000 people in a global pandemic in 2009, have identified one of the key genes governing an individual's susceptibility to infection from the influenza virus.

The discovery helps to explain why some people become dangerously ill when they catch the flu, while others experience only mild symptoms.

The study, published in the journal Nature, could help scientists to develop new anti-viral drugs, and to identify those most at risk from future flu pandemics.

Science correspondent Tom Feilden reports.

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