Low level of seroconversion after a novel influenza A/H1N1/2009 vaccination in Japanese patients with rheumatoid arthritis in the 2009 season
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We examined change in the antibody titre against pandemic influenza A/H1N1/2009 before and after vaccination in Japanese patients with rheumatoid arthritis. This observational study was conducted with the participation of five hospitals in Japan. A total of 89 patients with rheumatoid arthritis were included in this study. The seroprotection and seroresponse rates to vaccination with the pandemic influenza A/H1N1/2009 vaccine were analysed. The seroprotection rates prior to the vaccination were 5.6% in the Japanese patients with rheumatoid arthritis. The seroprotection rates after subcutaneous vaccination were 55.1%. The seroresponse rate after subcutaneous vaccination was 50.6% in the patients with rheumatoid arthritis. Both the seroprotection and seroresponse rates obtained after the vaccination with the pandemic influenza A/H1N1/2009 vaccine were low in Japanese patients with rheumatoid arthritis. We should realise that a vaccination against this newly emerged influenza virus may protect only half of the Japanese patients with rheumatoid arthritis in a real world.
KeywordsInfluenza A/H1N1/2009 Vaccination Rheumatoid arthritis
We thank for Ms. Asumi Hirata (Tochigi Prefectural Institute of Public Health and Environmental Science) for technical advice on the HI assays.
Conflict of interest
The authors have no conflicts of interest to declare.
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