Influenza vaccination of schoolchildren and influenza outbreaks in a school.

BACKGROUND The objective of this retrospective descriptive study was to determine whether the universal influenza vaccination for schoolchildren was effective in controlling influenza outbreaks in a school. A universal vaccination program for schoolchildren was started in Japan in the 1960s, but the government abandoned the program in 1994 because of lack of evidence that the program was effective in preventing influenza in schoolchildren. METHODS Influenza vaccine coverage rates, total numbers of class cancellation days, and absentee rates were reviewed in a single elementary school during the 24-year period during 1984-2007. RESULTS The mean number of class cancellation days and the mean absentee rate in the compulsory vaccination period (1984-1987; mean vaccine coverage rate, 96.5%) were 1.3 days and 2.5%, respectively, and they increased to 8.3 days and 3.2% during the quasi-compulsory vaccination period (1988-1994; vaccine coverage, 66.4%). In the no-vaccination period (1995-1999; vaccine coverage, 2.4%), they were 20.5 days and 4.3%, respectively, and in the voluntary vaccination period (2000-2007; vaccine coverage, 38.9-78.6%), they were 7.0-9.3 days and 3.8%-3.9%. When minor epidemics were excluded, there was a significant inverse correlation between the vaccine coverage rates and both the number of class cancellation days and absentee rates. CONCLUSIONS The universal influenza vaccination for schoolchildren was effective in reducing the number of class cancellation days and absenteeism in the school.