ABSTRACT
Introduction: Epidemiologic evidence on childhood vaccination is scarce in Japan. Our aim was to investigate the vaccination completion rate and risk factors of incomplete vaccination. <br>Methods:This study was a secondary analysis of the database developed for a childhood infection study of 2368 attendants of 18-month health checkups in one city in Japan. The data of vaccination history included bacillus Calmette-Guérin, diphtheria-pertussis-tetanus, measles-rubella, and polio. A total of 1622 children were included in analyses after 746 were excluded because a large portion of their data was missing, and because their birthweight was <2500 g or their gestational age, <37 weeks. <br>Results:The overall vaccine completion rate was 79.3%. The factors significantly associated with incomplete vaccination by multivariate logistic analysis were two or more children living together, child care attendance, parents’ smoking habits and absence of exclusive breastfeeding at 4-month health checkups. As the number of risk factors for hospital admission due to infections increased, the vaccine completion rate tended to decrease. <br>Conclusion:Families with children who attend child care facilities and with two or more other children should be provided with more information regarding vaccination and positive health behaviors in general.