Flu Drug Tamiflu Fares Well in Testing (AP)

By MARGIE MASON, AP Medical Writer

SINGAPORE - The flu drug Tamiflu can prevent deaths in mammals infected with bird flu, suggests a new study that offers clues to the ideal dosage and duration needed for people, scientists said Wednesday.

Health experts have touted the antiviral Tamiflu as the most effective medicine available to fight bird flu, and countries worldwide have been racing to stockpile it in case the virus mutates into a form easily spread among people. But little is known about how much Tamiflu should be given to a person who has caught the current bird flu.

In the study, ferrets given the drug after being infected with the deadly H5N1 virus circulating in Vietnam all survived, said Elena Govorkova of St. Jude Children's Research Hospital in Memphis, Tenn. She presented the research during a two-day bird flu conference in Singapore.

The findings illustrate the benefits of early treatment and are in line with the limited research published about using the drug to fight the virus in humans, according to an abstract of the study.

The research will be used to create models to help predict how much Tamiflu people would need to take and for how long if a new pandemic strain emerges, said David Reddy of Swiss-based Roche Holding AG, which makes the drug.

After being infected for four hours, ferrets were given a dose equal to half the conventional human dosage for five days. It saved their lives. A higher dose was also given to ferrets 24 hours after being infected. Again, all of the ferrets given the drug survived, while those not treated all died.

The news wasn't as promising for human vaccine development, another front in the preparation for a potential flu pandemic.

Dr. James D. Campbell of the University of Maryland Center for Vaccine Development in Baltimore, said worldwide vaccine production capacity is still low. And getting the vaccine where it's needed if there's a pandemic will be time-consuming, he said.

"First you have to make the vaccine seed virus, then you have to produce large quantities of the vaccine, get the vaccine through the regulatory authorization, distribute the vaccine and actually vaccinate people," said Campbell, who is closely involved in U.S. vaccine trials. "And then wait the weeks that it takes after vaccination before the antibodies get to the level that would lead to protection."

Early tests indicate the vaccine currently under development is safe, but effective in only about 50 percent of patients. It also requires a dose 12 times stronger than a regular annual flu shot. Two shots are also required instead of one.

Campbell said the first large tests were set to begin this year on a new vaccine that won't rely on chicken eggs to produce, a process that is also time-consuming.