U.S. and Hong Kong (2006)

U.S. Department of Health and Human Services
National Institutes of Health (NIH) News

National Institute of Allergy and Infectious Diseases (NIAID)

FOR IMMEDIATE RELEASE
Thursday, October 12, 2006

CONTACT:
NIAID News Office
301-402-1663

News Advisory:
Updates on Pandemic Flu Vaccine Trials to be Presented at 44th Annual IDSA Meeting

Preliminary results from clinical trials testing two different pandemic flu vaccine approaches — one a prime-boost strategy using different subtypes of H5N1 vaccines, the other an H5N1 vaccine delivered into the skin (intradermal) rather than the muscle — will be presented at the 44th Annual Meeting of the Infectious Diseases Society of America being held in Toronto Oct. 12-15. The presentations are scheduled for a late-breaker session on Friday afternoon, Oct. 13th.

Funding for the trials comes from the National Institute of Allergy and Infectious Diseases (NIAID), one of the National Institutes of Health. Reporters may call the NIAID News Office at 301-402-1663 to speak with NIAID Director Anthony S. Fauci, M.D., who is available to comment and provide perspective on these preliminary findings.

Preliminary Results Suggest Priming Boosts Immune Responses to Variant H5N1 Vaccine

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One such alternative is to prime people ahead of time with a related vaccine so that only a single dose of vaccine is required when the pandemic emerges. A team of researchers led by University of Rochester Medical Center investigators Nega Ali Goji, M.D., and John J. Treanor, M.D., recently tested this hypothesis. They compared the immune response to a single 90-microgram dose of one variant of avian flu vaccine in two groups of adults: those who had received a different variant of H5N1 avian flu virus vaccine some eight years earlier and those without pre-exposure to any H5N1 virus or vaccines.

In late 1997-98, soon after the first case of direct bird-to-human transmission of an H5N1 flu virus occurred in Hong Kong, NIAID funded the production of an experimental vaccine made from the Hong Kong virus and tested it in a small clinical trial conducted at the University of Rochester in healthy adults (see reference). Thirty-seven individuals who received two doses of the Hong Kong H5N1 vaccine in that trial served as the "primed" population in the current study.

The booster dose in the current study — an experimental inactivated H5N1 virus vaccine produced for NIAID by sanofi pasteur, the vaccines business of the sanofi-aventis Group of Paris — is based on an H5N1 flu virus from Vietnam. The Hong Kong virus is related to the Vietnam virus but belongs to clade 3, which refers to its branch on an evolutionary tree of the H5N1 viruses in Asia, while the Vietnam virus belongs to clade 1.

In their trial, the Rochester team found that more than twice as many of the individuals who had received the priming dose of clade 3 H5N1 vaccine responded with substantial antibody levels to a single dose of clade 1 H5N1 vaccine than did those with no prior H5N1 exposure. Dr. Treanor says that these early but promising data indicate that priming with an antigenic variant vaccine before a pandemic occurs may be one strategy used to help control a pandemic.

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