A federal advisory committee on Tuesday recommended approval of the first bird flu vaccine for humans, despite concerns about its safety and evidence that the shots won't protect most people.
The panel said although the vaccine had significant shortcomings, it was safe and effective for use during a pandemic or in high-risk situations, such as military deployment to regions facing an outbreak.
The vaccine, produced by the French drug company Sanofi-Aventis, won't be sold commercially. The government plans to buy and stockpile enough doses for 20 million people, including healthcare workers and emergency personnel.
Panel member Robert Webster, chairman of the department of virology and molecular biology at St. Jude Children's Research Hospital in Memphis, Tenn., said the vaccine would be better than nothing.
"We need this pre-pandemic stockpile," he said. "It worries me that if we don't license this vaccine, what are the consequences?"
Norman Baylor, director of the FDA's vaccine office, told the panel that the vaccine was a stopgap measure. "There are numerous vaccines under development that are potentially better than this one," he said.
The Food and Drug Administration is not required to follow the advice of its outside experts but typically does.
The bird flu strain known as H5N1 originated in Asia. Although it rarely infects people, experts fear a mutation could make it easily transmissible, triggering a pandemic. From the start of 2003, 167 people, mostly in Asia, have died of the virus, according to the World Health Organization.
The Department of Health and Human Services has funded research of more than 30 potential bird flu vaccines.
In clinical trials, a two-shot series of the Sanofi vaccine provided protection in 45% of adults who received the highest dose, according to an FDA analysis this week. An interim analysis published in the New England Journal of Medicine last year said the vaccine protected 54% of adults in a clinical trail.
The protection was well below the level of provided by other approved vaccines. The seasonal flu vaccine, for example, protects 70% to 90% of people who get it. The FDA typically wants to see an antibody response in at least 70% of vaccine recipients.
No serious side effects were detected among the 450 healthy adults who participated in a clinical test. However, some panel members were concerned that the trial was too small to reveal rare side effects.
Some experts also worried about possible allergic reactions to the vaccine because it requires a massive dose -- 12 times that of the seasonal inoculation.
The committee recommended close monitoring of the people who receive the vaccine to spot unexpected side effects and to further evaluate the vaccine's effectiveness.