Adverse events of 2009 novel pandemic influenza (A/H1N1) vaccibation – comparison with seasonal and simultaneous vaccination –
Vaccination against novel pandemic influenza (A/H1N1) is available in Japan since October 2009. During the 2009－10 influenza pandemic, this vaccine was administered either separately or simultaneously with seasonal influenza vaccine. In the present study, we investigated the adverse events associated with novel pandemic influenza vaccination, and compared these events with those of seasonal influenza vaccination and simultaneous vaccination. We also investigated the factors associated with the incidence of adverse events. Although no serious adverse events were observed in any case (total cases, 470 ; 95 received pandemic, 134 received seasonal, and 241 received simultaneous vaccinations), some subjects developed local and systemic reactions. Local reactions like erythema and swelling and systemic reaction like fatigue were observed. Among the subjects who experienced local reactions, those who received novel pandemic vaccination showed significantly lower incidence of adverse events than those who received other vaccinations; among the subjects who experienced systemic reactions, no statistical difference was observed. Odds ratios influencing the incidence of adverse events were calculated according to the potential risk factors using multiple logistic regression analysis. Among the subjects who received the novel pandemic influenza vaccination, females exhibited higher odds ratio (8.29 times) than males. With regard to the age groups, the odds ratios of subjects of all age groups were higher (3.74－9.28 times) than that of subjects over 50 years who received simultaneous vaccination. Moreover, the odds ratios of past adverse events were significantly high (10.9－ 15.9 times), regardless of the type of vaccination. (Accepted on July 1, 2010)
