Experiments with a deadly flu virus, suspended last year after a fierce global debate over safety, will start up again in some laboratories, probably within the next few weeks, scientists say.
The research touched off a firestorm in 2011 when it became known that two groups, one in the Netherlands and another in the United States, had genetically altered a dangerous bird flu virus to make it more contagious in mammals. Some scientists warned that a deadly pandemic could break out if the mutant virus leaked out of the lab accidentally or if terrorists stole it or made it themselves, using articles in scientific journals for the recipe.
The outcry led scientists conducting the experiments to declare a voluntary moratorium a year ago, in part to let research organizations and governments decide what safety rules to require.
Now, flu researchers say, the moratorium should end because most countries have rules in place. A letter from 40 scientists — the same ones who called the moratorium last year — was published on Wednesday in the journals Science and Nature, saying it is time for the work to begin again in countries ready to allow it.
But the United States, which pays for much of the flu research both at home and abroad, has not yet released new guidelines. So scientists in America will not be able to resume experiments yet, nor will those in other countries who depend on grant money from the United States.
During a telephone news conference on Wednesday, Ron Fouchier, a virologist who conducted some of the flu experiments at Erasmus Medical Center in the Netherlands, said the scientists were lifting the moratorium without waiting for guidelines from the United States.
“How long do you want us to wait?” Dr. Fouchier asked. “If this was the Netherlands, would the U.S. wait? Should all countries really wait for the U.S., and why?”
He said his laboratory would resume research within a few weeks. Although he receives research money from the National Institutes of Health in the United States, funding from other sources will allow him to go ahead, he said. Other researchers in the European Union would be free to pick up the research if they had funding that did not come from the United States government, he said. Laboratories in China and Canada may be ready to start up, but Japan, like the United States, is still working on new guidelines, researchers said during the teleconference.
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said the Department of Health and Human Services was reviewing new guidelines, and that he expected them to be approved in weeks. The guidelines will specify the laboratory conditions under which this type of research is permitted and require that experiments have a potential benefit for public health.
The experiments involve a type of bird flu virus called H5N1. It does not often infect people, but appears unusually deadly when it does. Of 610 known cases in people since 1997, slightly more than half have been fatal. But the real death rate is not known and could be lower than half because some mild cases may go uncounted.
So far, H5N1 has rarely spread from person to person. People who fall ill have nearly always caught it from poultry. But flu viruses mutate a lot, and the fear has been that H5N1 will somehow become more contagious in humans.
The debated experiments, by Dr. Fouchier and Dr. Yoshihiro Kawaoka, at the University of Wisconsin-Madison, involved ferrets, which are considered a good model for flu research because they react to the virus in much the way people do. Researchers can infect ferrets with H5N1 by squirting the virus into their noses or lungs, but then the animals normally do not infect one another. However, by genetically manipulating the virus, researchers created a form that became airborne and spread from ferret to ferret. Its transmissibility set off alarms.
Advocates of the research insist it can be done safely. And they say it is necessary so scientists can recognize changes in naturally occurring viruses that are dangerous and signal the need to eradicate infected animal populations. Understanding the viruses better should also help researchers develop more effective vaccines and antiviral drugs, Dr. Fouchier said.
He said other scientists could be given samples of the mutant virus for research only with the permission of Erasmus Medical Center, the National Institutes of Health and virus experts at the Mount Sinai Medical Center in Manhattan.
But some scientists still have reservations. Michael T. Osterholm, director of the Minnesota Center of Excellence for Influenza Research and Surveillance at the University of Minnesota and a member of a United States biosecurity board, said that he thought the research should go on, but that details should not be published for fear others would try to replicate it without safety precautions.
“The work they’re doing is really important,” he said, “but I don’t see it as work I want in the hands of every potential gene jockey out there.”
