This week, the U.S. Food and Drug Administration (FDA) has scheduled a two-day meeting of its Vaccines and Related Biological Products Advisory Committee, and among the agenda items will be a discussion of the safety and effectiveness of Sanofi AventisÃ¢â‚¬â„¢ H5N1 inactivated influenza (bird flu) vaccine. In advance of the meeting, the FDA has released several briefing documents that have called into question the effectiveness of the vaccine.
FDA researchers determined that Ã¢â‚¬Å“there were no significant safety signals that would preclude administration of this vaccine to additional persons.Ã¢â‚¬Â However, they also found that the vaccine was not as effective as previously thought. Last year, a New England Journal of Medicine study found that only 54 percent of trial patients had developed an effective immune response. The FDAÃ¢â‚¬â„¢s analysis of the same study, put forth in the new briefing documents, found that only 45 percent of patients whoÃ¢â‚¬â„¢d received the highest dosage (a series of two shots, 90 micrograms each) developed an effective immune response to the virus.
According to the FDA, the original NEJM study concluded that Ã¢â‚¬Å“the higher the dosage of vaccine, the greater the antibody response produced.Ã¢â‚¬Â The agency found that the 90-microgram dosage was by far the most effective treatment.
According to the agency, Ã¢â‚¬Å“Presently, there are no vaccines licensed in the U.S. for avian influenza viruses such as H5N1 that have the potential to be the next pandemic strain. FDA is working with other government partners such as the National Institutes of Health (NIH), the Centers for Disease Control (CDC), and the Department of Health and Human Services (DHHS) as well as the vaccine industry to diversify and strengthen influenza vaccine manufacturing, and provide flexible and rapid regulatory pathways which will lead to the licensure of pandemic influenza vaccines.Ã¢â‚¬Â