Abstract
The efficacy of influenza vaccination was examined by an anonymous questionnaire among vaccinees and non-vaccinees at 15 Health Welfare Centers in Chiba in March 2004. The 424 (male 148, female 224, unknown 52) vaccinees received influenza vaccine in November 2003. There were 82 non-vaccinees (male 29, female 38, unknown 15). During the following winter season after vaccination, febrile episodes were observed in 30/424 (7.1%) vaccinees (male 6, female 17, unknown 7) and 12/82 (14.6%) non-vaccinees (male 5, female 7). The difference between these figures was significant (chi-square test, p<0.05). Self reported local reaction (swelling) was observed in 18/148 (12.2%) male vaccinees and in 80/224 (35.9%) female vaccinees. There was a significant difference (p<0.001). The results indicated that influenza vaccine could decrease febrile episodes during the winter season, but the high incidence of local reaction in females should be considered.
