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Novel H1N1 Vaccine Found Effective for Most Age Groups

Vaccine developed and tested in China confers protective immune response for ages 12 to 60

WEDNESDAY, Oct. 21 (HealthDay News) -- A new influenza A (H1N1) vaccine developed in China successfully generated a protective immune response in subjects ranging in age from 12 to 60 years, according to a study published online Oct. 21 in the New England Journal of Medicine.

Feng-Cai Zhu, M.D., of the Jiangsu Provincial Center for Disease Control and Prevention in Nanjing, China, and colleagues randomized a group of 2,200 subjects to receive a dose of a split-virus, inactivated candidate vaccine (or placebo), of whom 2,103 received a second dose (or placebo) 21 days later. The vaccine was tested in three dosages (7.5, 15, or 30 µg) with or without alum adjuvant.

Most subjects getting the single 15 µg dose without alum adjuvant achieved a hemagglutination-inhibition titer of 1:40 or more by day 21, which varied by age group as follows: 74.5 percent for the age group 3 to 11, 97.1 percent for 12 to 17, 97.1 percent for 18 to 60, and 79.1 percent for 61 and older. By day 35, the percentages achieving 1:40 titer were 98.1, 100, 97.1, and 93.3 percent, respectively. There were no serious adverse effects, though mild injection site and system reactions were observed.

"These data suggest that a single dose of 15 µg of hemagglutinin antigen without alum adjuvant induces a typically protective immune response in the majority of subjects between 12 and 60 years of age," the authors write.

Two study authors reported being employees of the Hualan Biological Bacterin Company, which supported the study.

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