TUESDAY, Feb. 27, 2007 (HealthDay News) -- U.S. Food and Drug Administration advisers voted Tuesday to recommend approval of the first bird flu vaccine, even though it would protect only 45 percent of people exposed to the virus.
The vote came after FDA officials said that the vaccine could still play an important role in protecting against the likelihood of a flu pandemic, despite its limited effectiveness.
But one infectious disease expert, who was not on the advisory panel, said approval of the vaccine should only be a temporary measure until a better vaccine is developed.
"It's better than nothing to have something," said Dr. Philip Tierno, director of clinical microbiology and immunology at New York University Medical Center.
The efficacy rate of 45 percent is too low, Tierno said. "The usual efficacy for a flu vaccine is between 75 and 90 percent," he said. "This vaccine is half as effective as the best seasonal flu vaccine we have. This should be a temporary move until we get something better."
In separate votes, the panel said the vaccine, made by Sanofi Aventis SA, is both safe and effective, the Associated Press reported.
The FDA is not required to follow the advice of its advisory panels, but it typically does. This vaccine is the first designed to protect against the H5N1 bird flu strain that has sought FDA approval.
Despite the lack of FDA approval, the U.S. government has already started stockpiling the vaccine. The plan is to have enough doses to protect 20 million people, including emergency workers and others, in the event of a flu pandemic and to use it until a more effective vaccine is developed. The vaccine will not be commercially available, according to the AP.
Although not required, FDA approval would give the agency's opinion on the vaccine's safety and effectiveness, Dr. Jesse Goodman, FDA's chief of biologic products, told the AP.
In a clinical trial, the vaccine seemed to protect just 45 percent of adults who received the highest dose. An earlier analysis of the same data suggested the vaccine would protect 54 percent of patients. The FDA would like to see a response rate of at least 70 percent, the news service said.
''The more antibodies, the better. But even at lower levels, there is a possibility of protection,'' Goodman said.
Despite its limited effectiveness, the vaccine still could prove better than nothing in an outbreak, said Norman Baylor, director of the vaccine office at the FDA, according to the AP.
''The benefit of having a licensed vaccine against a potential pandemic influenza virus strain must be weighed against the risk of having no vaccine at the time of an inevitable influenza pandemic,'' Baylor told the advisory panel. Baylor added that even a single dose of the two-shot vaccine could help combat the deadly bird-flu strain.
Tierno said a flu pandemic could be catastrophic. "If you use this vaccine coupled with the antiviral Tamiflu and statins, perhaps you can prevent the flu from moving across the United States," he said. "You need something, and this is better than nothing, and if they are pursuing a newer, better vaccine, then it's OK."
While bird flu has been devastating poultry in Asia for several years, the World Health Organization has recorded only 167 human deaths linked to the disease. But health experts are worried that the virus could mutate into a form that would be easily transmittable from person to person, unleashing a pandemic.
For more information on bird flu, visit the U.S. Centers for Disease Control and Prevention.