Abstract
For preparedness of H5N1 pandemic, several types of influenza prototype vaccine have been developed in several countries. Alum-adjuvanted whole virus influenza vaccine, which has been developed in Japan, had excellent priming effect after two doses, and the third shot of the heterologous strain to the subjects primed two years previously elicited strong and broad cross immunity. Moreover, solicited local and general reactions were acceptable. However, influenza A (H1N1) 2009 virus, which had much different antigenicity from A Russia lineage, was detected in April 2009 and developed pandemic. According to clinical studies of (H1N1) 2009 monovalent vaccine in adults, split vaccine could induce appropriate secondary immune responses after one dose. These results suggested that adults had immune memory to (H1N1) 2009 virus, and that vaccination strategy to this virus was efficient by using seasonal influenza vaccination strategy. Additionally, since WHO speculates (H1N1) 2009 virus could be endemic in near future, the (H1N1) 2009 virus-derived strain is included in the 2010/11 seasonal influenza vaccine.
