Immunogenicity of a monovalent pandemic influenza A H1N1 vaccine in health-care workers of a university hospital in Japan.

Abstract

A phase III observational study evaluating a single-dose of an inactivated, split-virus, unadjuvanted AH1pdm vaccine in HCW was conducted. A safe and effective vaccine was needed after the emergence of AH1pdm in April 2009. We analyzed the immunogenicity and safety of the vaccine. A total of 409 subjects were enrolled and given 15 μg hemagglutinin antigen by s.c. injection. Antibody titers were measured using hemagglutination-inhibition antibody assays before vaccination and 28 days after. The co-primary immunogenicity end-points were the proportion of subjects with antibody titers of 1:40 or more, the proportion of subjects with either seroconversion or a significant increase in antibody titer, and the factor increase in geometric mean titer. We collected 389 pair samples. Antibody titers of 1:40 or more were observed in 148 of 389 subjects (38.0%, 95% CI: 33.2-42.9). The immunogenicity was also confirmed in other end-points, but was not sufficient and was lower than in previous reports. A total of 96 of adverse events was reported: 51 local events and 57 systemic events. There were 12 subjects with both local and systemic events. Nearly all events were mild to moderate except in four subjects. A single 15-μg dose of AH1pdm vaccine did not induce sufficient immunogenicity in HCW, with mild-to-moderate vaccine-associated adverse events. We need to consider further improvement of the AH1pdm vaccine program in HCW for the prevention of nosocomial infection, as well as for the benefit of HCW.

• Authors: Hidetoshi Igari, Shunsuke Segawa, Akira Watanabe, Akiko Suzuki, Mariko Watanabe, Takayuki Sakurai, Fuminobu Kuroda, Masaharu Watanabe, Koichiro Tatsumi, Mikio Nakayama, Toshinori Nakayama, Kazuo Suzuki, Takeyuki Sato
• Journal: Microbiology and immunology (Microbiol Immunol) Vol. 54 Issue 10 Pg. 618-24 (Oct 2010) ISSN: 0385-5600 [Print] Australia
• PMID: 21118299 (Publication Type: Clinical Trial, Phase III, Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2010 The Societies and Blackwell Publishing Asia Pty Ltd.

Chemical References

• Antibodies, Viral
• Influenza Vaccines

Topics

• Adult
• Aged
• Antibodies, Viral (blood)
• Female
• Health Personnel
• Hospitals, University
• Humans
• Influenza A Virus, H1N1 Subtype (immunology)
• Influenza Vaccines (adverse effects, immunology)
• Japan
• Male
• Middle Aged
• Pandemics
• Prospective Studies
• Vaccination