It’s better than nothing, federal health advisers said Tuesday in urging approval of the first bird flu vaccine as a stopgap against a potential pandemic until more effective vaccines can be developed.
The panel said in a 14-0 vote that the vaccine was effective, despite evidence it wouldn’t protect most people against the deadly H5N1 strain of bird flu. The panel then voted that it was safe.
“I hope we never have to use it,” said panel member Dr. Melinda Wharton, deputy director of the national immunization program at the Centers for Disease Control and Prevention. “But this is the vaccine we have now.”
The votes came after Food and Drug Administration officials said the Sanofi Aventis SA vaccine could play an important role in protecting against a pandemic, considered ever more likely, despite its limited effectiveness.
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.
Long way to go
Dr. Jack Stapleton of the University of Iowa Hospital Clinic called the vaccine “better than nothing.” Fellow panelist Robert Webster of St. Jude Children’s Research Hospital in Memphis likened the vaccine to a child’s first step — “very tentative and very necessary to do” — before adding, “There is a long way to go.”
The recommendation now goes to the FDA, which 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 first responders in a pandemic. It would be used until better vaccines could be developed.
Though not required for the limited usage planned, FDA approval of the vaccine would state the agency’s opinion on its 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 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 latter analysis relied on tougher standards to show it worked, Sanofi said. Still, 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 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,” said Norman Baylor, director of the FDA’s vaccine office.
The vaccine’s modest protective effects 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 additional studies under way 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.
Scientists also are studying the development of cell-based vaccines, which would be faster to produce in an outbreak of deadly flu than are current egg-based vaccines.
Sanofi’s Kenneth Guito called the Paris-based 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 spreads easily from person to person, sparking a pandemic.