The analysis of mucosal immune responses induced by intranasal administration of an inactivated influenza virus vaccine in human

INTERVENTION: Intranasal administration of an inactivated whole‐virus vaccine (A/H5N1, 45ug HA/dose) is performed twice with a 3 week interval. About a half year later, the same vaccination will be performed once more. For the characterization of S‐IgA antibodies, a few participants will receive two additional vaccinations after the last vaccination. Intranasal administration of an inactivated whole‐virus vaccine (A/H5N1, 45ug HA/dose) with CVP is performed twice with a 3 week interval. About a half year later, the same vaccination will be performed once more. For the characterization of S‐IgA antibodies, a few participants will receive two additional vaccinations after the last vaccination. CONDITION: Influenza PRIMARY OUTCOME: Neutralization, HI, and HA‐specific antibody titers before and after intranasal vaccination.; The proportion of memory B cell or plasma cell in peripheral blood mononuclear cells, and the cytokine profile.; The analysis of the antibody repertoire induced by the intranasal vaccination.; The characterization of secretory IgA antibodies in nasal mucus.; Survey on side reaction after vaccination. INCLUSION CRITERIA: Healthy adult volunteers who are interested in the open recruitment for our study, and agree with our study contents, as confirmed by giving their informed consent before the onset of the study.