In a darkened conference room in Malta in September, a Dutch scientist announced to a virology meeting that he had created a mutated strain of H5N1 bird flu which had the potential to spread between humans.

Dr Ron Fouchier, from the Erasmus Medical Center in Rotterdam, said his team had introduced a number of genetic variations - around five - which had enabled the virus to pass between ferrets - the best animal model we have for testing whether the virus will infect humans.

So while it is not certain that the Dutch team had created a deadly human strain of bird flu, it seems to be a real possibility.

This story made headlines today but has been around for some time. The Erasmus Medical Center issued a press statement last month in which Fouchier said the discovery could help prevent a pandemic: "We now know which mutations to watch for in the case of an outbreak and we can then stop the outbreak before it is too late. Furthermore, the finding will help in the timely development of vaccinations and medication."

The assembled virologists in Malta were told the full data would be published in due course in the journal Science. But it is being held up by a review being undertaken by the US National Science Advisory Board for Biosecurity (NSABB).

The concern is that the details of the research could be misused in the wrong hands. The NSABB has asked Science to publish only an abbreviated version.

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