Dr. Ron Fouchier, one of the two researchers who developed and studied mutant forms of avian H5N1 influenza that’s transmissible through the air, provided new details of his findings at a conference this morning in Washington. He explained that the mutant virus is not nearly as deadly or transmissible as many people have supposed.
This new information seems to be, at least in part, at the root of the different conclusions recently reached by the U.S. National Science Advisory Board for Biosecurity (NSABB) and by a group organized by the World Health Organization (WHO) on whether detailed methods of the H5N1 mutant research should be released to the public. During the past few days, the National Institutes of Health called on the NSABB to meet again to hear the new data and see if it would change the Board’s decision to keep the methods sections of the papers under wraps, Dr. Anthony Fauci said at today’s meeting.
“This virus does not kill ferrets that are sneezed on [by ferrets already infected with mutant H5N1], and if it was released it is unlikely that it would spread like wildfire, and to extrapolate that it would spread like wildfire in humans is really farfetched at this stage,” said Dr. Fouchier, a researcher at Erasmus University in Rotterdam. “This virus does not spread like a pandemic or seasonal influenza virus,” he said in a session that dealt with H5N1 issues during a meeting on Biodefense and Emerging Diseases sponsored by the American Society for Microbiology. He called any notion that the mutant avian H5N1 flu he created could transmit readily in aerosolized form from ferret-to-ferret a “misperception.”
In addition, many people have had a second important misperception of the virus he’s studied: The H5N1 mutant strains he created are not highly lethal.
“It’s very clear that H5N1 is highly lethal in chickens, but in mammals that’s not the case.” The mutant form of the virus will kill a ferret if you place a large dose of the virus—a million virions—directly into the animals lower respiratory tract. That kills the animal in about 3 days, he said. But if a more modest and typical inoculum gets introduced intranasally to a ferret, the animal simply gets a flu-like illness but recovers. “We saw no severe disease in any of the seven animals that received virus by aerosol,” he said.
A third, heartening observation he’s made about how mammalian-transmissible H5N1 behaves is that ferrets exposed to seasonal flu before exposure to the H5N1 mutant “are fully protected against severe disease.” His conclusion from this: “It’s unlikely that humans have no cross protection to H5N1, so very few would develop severe disease. Most [people] would be protected by cross-protective immunity.”
According to Dr. Fauci, director of the National Institute of Allergy and Infectious Disease, these clarifications from Dr. Fouchier first came to light earlier this month during a meeting on H5N1 convened by the WHO in Geneva. These new data, as well as the recommendations made by the WHO group, led Dr. Fauci to ask the NSABB to reconvene.
“The NIH continues to support the NSABB recommendations regarding the original manuscripts [to publish redacted versions of the papers], and supports revision of the manuscripts to include new data and explicit clarifications of old data,” Dr. Fauci said. “There was obviously a disagreement in the recommendations between Geneva and the NSABB. There was a strong feeling to reconvene the NSABB to give them the benefit of the same information and discussion as in Geneva.”
–Mitchel Zoler (on Twitter @mitchelzoler)