ABC Medical Unit 'Voices of Reason':
H1N1 Mutation in China

"Voices of Reason" is a regular feature, taking a brief look at how some of the country's top medical experts view developing health-news stories.

For months, doctors and public health experts have expressed concerns that a mutation of the H1N1 swine flu virus could pose a serious threat to human health.

On Wednesday, reports from China of eight patients with a mutated strain would seem to have given life to these fears. But infectious disease experts say that while these cases may indeed represent mutation of the viral strain, they are not a cause for panic.

"Viruses mutate. It's what they do," said Philip Alcabes at CUNY Hunter College in New York and author of the book "Dread," which explores pandemics through history. "Flu viruses mutate quite a lot."

And while all viral mutations are genetic changes, these changes are not necessarily more dangerous.

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"There have been several mutations of uncertain significance," said Mary Nettleman at Michigan State University. "Last week ... WHO reported some from Norway." And of course, as Nettleman points out, mutations are "how we got H1N1 in the first place."

"It is incomprehensible to think this virus won't mutate," said Gregory Poland at the Mayo Clinic. "The nature of how these viruses replicate is such that mutations are guaranteed to occur -- the question is whether the mutated viruses are 'fit' ... and do they cause disease or antiviral resistance. It is too early to answer those questions on the basis of the current data."

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According to Chinese officials, the mutated viruses can still be controlled with antiviral drugs. The big concern is whether the virus will mutate into a form that is no longer treatable with available medications.

"The significance for humans would be very difficult to predict," said John Treanor, professor of microbiology and immunology at the University of Rochester in New York. The only exception would be mutations that convey resistance to [antivirals]. "Since that mutation is so common in seasonal H1N1 viruses, it is a little bit of a surprise that we haven't already seen it extensively in the 2009 H1N1."