Avian Flu Vaccine Safe and Effective in Clinical Trial

Low doses of vaccine induce antibodies in up to 78 percent of subjects

THURSDAY, Sept. 7 (HealthDay News) -- A phase I trial of an H5N1 influenza vaccine shows that low doses of vaccine are safe and can induce antibody responses in up to 78 percent of subjects, according to a study published online Sept. 7 in The Lancet.

Jiangtao Lin, M.D., of the Chinese-Japanese Friendship Hospital in Beijing, China, and colleagues conducted a phase I clinical trial of an inactivated whole-virion influenza A (H5N1) vaccine on volunteers aged 18 to 60 years old. Twenty-four volunteers each were randomized to receive two doses of a placebo or vaccines containing 1.25, 2.5, 5 or 10 micrograms of haemagglutinin plus an aluminum hydroxide adjuvant on days 0 and 28.

The researchers found that all doses of vaccine induced antibody responses after the first dose, with 78 percent seropositivity observed after two doses of 10 μg vaccine. The vaccine was well-tolerated at all doses, with no serious adverse events. Most reactions were mild and transient, with pain, swelling and fever being the most commonly reported side effects. The authors note that the 10 μg vaccine "met all European regulatory requirements for annual licensing of seasonal influenza vaccine."

"These findings identify a potential dose-sparing approach that could be crucial for a global supply of pandemic vaccine," Iain Stephenson, M.D., of the Leicester Royal Infirmary in the U.K., writes in an accompanying editorial.

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