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U.S. Health Secretary Says More Bird Flu Vaccines Coming

HHS Secretary Michael Leavitt (©AP/WWP)

Washington – U.S. health agencies are continuing to develop vaccine alternatives that will protect against the evolving avian influenza virus, U.S. Secretary of Health and Human Services Michael Leavitt said March 6.

In 2005, the National Institute of Allergy and Infectious Diseases (NIAID) successfully tested a vaccine that produced an immune response to one strain of the H5N1 virus that swept out of Southeast Asia, through Central Asia and into Europe and Africa.

That vaccine was developed from a sample of the H5N1 viral strain collected in Vietnam. As the virus has continued to spread through bird populations in wider areas, however, it has changed. Vaccines must change too.

“In order to be prepared, we need to continue to develop new vaccines,” said Leavitt at a medical conference focused on immunization.

The health secretary said U.S. and international research partners are working to create “seed viruses,” or reference strains, of candidate viruses that are used in vaccine manufacture.

“The H5N1 virus has continued to [evolve] over the past 18 months. We continue to monitor its evolution.” Leavitt said. “We will have seed viruses reflecting this drift that can be quickly available for vaccine testing and production.”

Leavitt said researchers at the U.S. Centers for Disease Control and Prevention (CDC) have worked to keep pace with the transcontinental travels of H5N1 as it has migrated out of its Asian point of emergence since 2003.

“The CDC has developed another seed virus similar to the virus now circulating in parts of Asia, Europe and Africa,” Leavitt said.

After successful human testing conducted by NIAID and research partners showed that the first trial vaccine was effective, production began, creating a stockpile now of 8 million doses.

The fear is that the vaccine could be ineffective if the virus has mutated significantly from the sample on which the serum was based.

According to the World Health Organization (WHO), 175 human cases of H5N1 infection have been detected since 2003, resulting in 95 deaths. All but one of the victims became infected, experts say, through direct contact with sick birds and their environs.

H5N1 does not transmit efficiently to humans in its current form, but if it does develop that capability, a global flu pandemic could result, experts warn.

Since the disease began spreading rapidly out of Asia in mid-2005, the international community has responded to the warnings and mobilized an effort to help bolster disease detection and surveillance in developing countries.

Surveillance of bird populations and stamping out infection when detected is considered the most effective way to stop the disease and prevent its movement into humans.

The United States has been a leader in mobilizing that international effort, and is the largest single donor to support anti-disease campaigns in other countries, having committed more than $330 million to various programs. (See related article.)

For additional information on the disease and efforts to combat it, see Bird Flu (Avian Influenza).

The full text of Leavitt’s prepared remarks is available on the department’s Web site.