Bird Flu Threat Rises
WHO Expert Panel: World 1 Step Closer to Killer Flu
Another Tick of the Pandemic Clock continued...
"There is no evidence of a big crisis," Rodier said at the news conference. "But there are enough elements to say there may be something going on. ... We have enough data to be concerned. At the same time we don't have enough data to be sure."
"In the last 18 months, we have seen an incremental increase in our concern," Stöhr said. "We do not know if a pandemic can occur next week or next year."
Killer Flu Pandemic: What Could Happen?
The H5N1 bird flu virus could, theoretically, become a pandemic flu virus overnight. That could happen if a person or animal were infected with a human flu virus and the bird flu virus at the same time. In that case, the viruses could "reassort" -- that is, swap genes.
On the other hand, what seems to be happening is that the H5N1 virus is only gradually learning how to pass more easily from human to human. That, Stöhr says, is giving us time to prepare. But when the virus does learn this trick, it's going to be hard to stop.
This last happened in 1968, when a new human flu virus appeared in Asia. It took six to nine months to reach the U.S. Today, it would probably take only three months.
Right now, the world has only 2 million doses of a new vaccine against H5N1 bird flu -- all in the U.S. Safety tests aren't yet complete. And it's not even clear whether the vaccine will really work against the strain of flu that eventually emerges.
Although the bird flu virus is extremely deadly to humans, it's likely that it would become less virulent if it adapted for human-to-human spread. But it could easily be as deadly as the worst flu virus yet: the pandemic flu of 1918 that killed 50 million people worldwide -- half of them young, healthy adults.
So what might happen? Michael T. Osterholm, PhD, MPH, is director of the Center for Infectious Disease Research at the University of Minnesota. He sketched out a likely scenario in the May 5 issue of The New England Journal of Medicine.