The H5N1 virus is known as a "bird flu" because it mainly affects birds, which also can transmit it to humans. But last year, two teams of scientists reported that the virus could be made to spread easily from ferret to ferret — an animal that has long been used as a stand-in for people in influenza research. An H5N1 virus that could pass easily from person to person would be entirely new, and more dangerous.
Citing bioterrorism concerns, a federal biosecurity advisory board recommended that key data from the experiments not be published, a move that troubles many scientists who worry it could stifle research and set a worrisome precedent. The journals considering publication of the papers, Science and Nature, have not yet done so.
Media reports about the controversy have been marked by frightening language, including the oft-repeated claim that the virus kills 60 percent of the people it infects. On Saturday, a New York Times editorial questioned whether the research should have been done in the first place, writing: "They created a virus that could kill tens or hundreds of millions of people if it escaped confinement or was stolen by terrorists."
But is that true? The Tribune contacted virologists and other influenza experts, including a member of the advisory board, to sort through the claims and offer some perspective.
Q: How deadly is the H5N1 virus? Does it really kill more than 60 percent of the people it infects?
A: "It's not clear," said Vincent Racaniello, a virologist at Columbia University. "What is clear is you cannot say the fatality rate is 60 percent."
The number comes from statistics compiled by the World Health Organization, which has collected information about nearly 600 cases of H5N1 virus infection in people since 2003. The WHO defines a confirmed case as a person who becomes quite ill after likely exposure to the H5N1 virus and had his or her infection confirmed by a lab accepted by the WHO. Of those people, about 60 percent died.
But the WHO numbers don't answer the question of whether some infected people don't become sick, or at least not sick enough to be swept into the WHO's statistics.
More than a dozen papers have been published on these issues, but so far there is no consensus. "A lot needs to be done before we know," said flu expert Robert Lamb, a professor of molecular and cellular biology at Northwestern University.
University of Michigan virologist Michael Imperiale, who sits on the National Science Advisory Board for Biosecurity that made the recommendation, said that even if the 60 percent number is off by a factor of 100, that is still a high fatality rate. "You are getting close to the 1918 pandemic," Imperiale said, citing a famously deadly flu pandemic that killed millions. "It is better to proceed cautiously."
Q: Why did the researchers do this research?
A: Scientists have wondered what it would take to make the H5N1 virus transmissible by air between people, rendering it far more dangerous. Because these sorts of experiments cannot be done ethically with humans, researchers use ferrets.
Virologist Ron Fouchier of Erasmus Medical Centre in the Netherlands reported at an influenza conference in Malta in September that his team found it took very few changes in the genetic sequence of the virus to make it spread by air from ferret to ferret.
While some have questioned the value of that research, Imperiale said it answered an important scientific question. "They showed that this flu virus, previously not thought to be spread, can be made to spread" from person to person, he said.
"We should be thanking these people for doing this," said virologist Robert Krug of the University of Texas at Austin, who said the research should be interpreted not as a bioterrorism threat but as a wake-up call. Public health officials monitoring the H5N1 virus can watch for evidence of these mutations, he said, allowing a quicker response.
Q: What effect will omitting key data from published reports have on the research?
A: Experts agree that many details about these experiments are already known, in part because of Fouchier's presentation. Less is known about the work done by another team, led by a researcher from the University of Wisconsin at Madison.
Beyond that, the technique used by Fouchier's team — selecting virus traits by serially infecting ferrets — has been used by influenza researchers since the 1930s. As Lamb said, "The cat is out of the bag and it is a ferret."
Nobel Laureate Peter Doherty, an influenza expert at St. Jude Children's Research Hospital, said it would be possible for a determined person to conduct similar experiments with several dozen ferrets and a sample of the H5N1 virus. "It is not something that is tremendously challenging," he said.
Imperiale agreed that the "barn door was open."
"Nothing anybody does is going to stop a determined person from doing harm, but we can at least put some impediments in their way," he said.
The problem, say some researchers, is that preventing complete publication of the research could inhibit other teams from trying to replicate the findings or push the science forward.
"Omitting the identity of the mutations that enable transmission does not put an impediment in the way of terrorists," Krug wrote in an email. "Rather it impedes surveillance and future research. Such an omission is not to the best interests of protecting people against the threat of this virus."