Pandemic bird flu may be only three mutations away

Cambridge University researchers have found some strains of deadly avian H5N1 influenza that are only three mutations away from being transmissible from human to human.

The research suggests that the airborne strain of influenza could evolve naturally in one person.

Derek Smith, one of the authors of the study, said that while the risk is present, it is difficult to determine if and when it could actually happen, PTI reports.

"With the information we have, it is impossible to say what the exact risk is of the virus becoming airborne transmissible among humans," Smith said, according to the Daily Telegraph. "However, the results suggest that the remaining three mutations could evolve in a single human host, making a virus evolving in nature a potentially serious threat."

The researchers used a mathematical model to assess various factors on whether the three mutations could evolve in a short chain of transmissions or in a single host. The results of the study were held back from publication for several months because American authorities believed the information could be a security risk.

"How much of a fitness cost these changes confer individually or when combined and in which species, will be important to establish before we can really assess how close we are to the H5 pandemic," Wendy Barclay, the chair in Influenza Virology at Imperial College London, said, according to PTI. "Hopefully more work from the biologists to help the mathematicians address how mutant influenza viruses with new properties evolve within a host will increase our ability to estimate the risks of pandemics."