WASHINGTON – Federal health advisers recommended Tuesday that the government approve the first bird flu vaccine as a stopgap measure, despite evidence it wouldn't protect most people.
In separate votes, the outside panel said the vaccine was both safe and effective. A vaccine must meet both standards to win FDA approval. The votes came after Food and Drug Administration officials said the Sanofi Aventis SA vaccine still could play an important role in protecting against the increased likelihood of a pandemic, despite its limited effectiveness.
"I am of the view that anything is better than nothing," said panel member Dr. Robert Couch, of Baylor College of Medicine in Houston, prior to the vote.
The FDA isn't required to follow the advice of its advisory committees, but usually does. The vaccine is the first against the H5N1 influenza strain to seek government approval.
The vaccine already is being stockpiled, even without FDA approval, for eventual interim use to protect emergency workers and others in a pandemic. It would be used until better vaccines could be developed. Though not required, FDA approval would state the agency's opinion on the vaccine's safety and effectiveness, said Dr. Jesse Goodman, FDA's chief of biologic products.
In a clinical trial, the two-shot series appears to provide protection to just 45 percent of adults who received the highest dose. An earlier, interim analysis of the same study had suggested it prompted a protective immune response in 54 percent of patients, when measured 28 days after getting the second of two shots. The FDA said it would like to see a response in at least 70 percent of those vaccinated against bird flu.
"The more antibodies, the better. But even at lower levels, there is a possibility of protection," Goodman told reporters on the sidelines of the meeting.
The government plans to buy and stockpile enough bird flu vaccine for 20 million people, including emergency and health care workers. The Sanofi vaccine wouldn't be sold commercially.
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.
"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 panel of experts. Baylor also said even a single dose of the two-shot vaccine could help combat the deadly bird-flu strain called H5N1.
The Paris-based company believes the benefits of the vaccine outweigh its risks. The FDA said the vaccine is safe but it remains unclear whether it's effective.
Effectiveness was measured by the antibodies patients developed against the flu strain. The results also appear to fall well below what's expected of seasonal flu vaccines. Those regular flu shots, for example, protect 75 percent to 90 percent of vaccinated adults younger than 65.
The newer analysis used final data, while the earlier study used interim results, Sanofi said. The later analysis also used tougher standards to show the vaccine works, according to company documents released by the FDA.
The modest protective effects of the vaccine were seen in patients who received two 90-microgram doses of vaccine. The two shots contain 12 times the 15-microgram dose contained in regular winter flu shots.
Already, there are further studies under way that are looking at the use of immune boosters, called adjuvants, to try to improve the effectiveness of the H5N1 vaccine. Eventually, adjuvants also might shrink the needed dose for a pandemic vaccine closer to what's now used in seasonal shots.
Sanofi's Kenneth Guito called the company's H5N1 vaccine "an important first step" in preparing for an outbreak of bird flu in humans. It would be for adults 18 to 64, although the company eventually would seek to expand that age range, Guito said.
Since it began ravaging Asian poultry farms in late 2003, the H5N1 strain of bird flu has killed at least 167 people worldwide, according to the World Health Organization. Health officials worldwide worry the strain could mutate into a form that easily spreads from person to person, sparking a pandemic.