Determinants of self-paid rotavirus vaccination status in Kanazawa, Japan, including socioeconomic factors, parents' perception, and children's characteristics.

BACKGROUND: Japan's National Immunization Program does not cover rotavirus vaccine and no government subsidies are available. This study aimed to measure the uptake of and determinants that influenced self-paid rotavirus vaccination, including socioeconomic status and relative poverty. METHODS: We conducted a cross-sectional study at health check-ups for all children aged 18 months in Kanazawa, Japan, between December 2017 and July 2018. Community nurses collected information on self-paid vaccination history, parents' perceptions of and recommendations for rotavirus vaccine, and socioeconomic status in interviews using a unified questionnaire. We used multivariable logistic regression to assess vaccine uptake and possible determinants. RESULTS: In total, 1282 participants were enrolled. The estimated rotavirus vaccine coverage was 72.9%. Perceptions that rotavirus gastroenteritis was serious and that the rotavirus vaccine was effective, pediatricians' recommendations, information from the city office, magazine and Internet articles, and higher parental education level were associated with higher rotavirus vaccine uptake. Lower household income was associated with decreased rotavirus vaccine uptake. Vaccine expense, fear of adverse reactions to the vaccine, number of household members and siblings, and children's characteristics were not correlated with rotavirus vaccination. Poverty was associated with decreased rotavirus vaccine uptake, even after adjustment for other determinants (adjusted odds ratio 0.49, 95% confidence interval: 0.26-0.90). CONCLUSION: Parents' perceptions, socioeconomic status, relative poverty, and pediatricians' recommendations are determinants of vaccination. This study suggests that appropriate information about rotavirus vaccine, subsidies for those of lower socioeconomic status, and national recommendations are necessary to achieve higher coverage.

Estimating rotavirus vaccine effectiveness in Japan using a screening method.

Rotavirus gastroenteritis is a highly contagious, acute viral disease that imposes a significant health burden worldwide. In Japan, rotavirus vaccines have been commercially available since 2011 for voluntary vaccination, but vaccine coverage and effectiveness have not been evaluated. In the absence of a vaccination registry in Japan, vaccination coverage in the general population was estimated according to the number of vaccines supplied by the manufacturer, the number of children who received financial support for vaccination, and the size of the target population. Patients with rotavirus gastroenteritis were identified by reviewing the medical records of all children who consulted 6 major hospitals in Saga Prefecture with gastroenteritis symptoms. Vaccination status among these patients was investigated by reviewing their medical records or interviewing their guardians by telephone. Vaccine effectiveness was determined using a screening method. Vaccination coverage increased with time, and it was 2-times higher in municipalities where the vaccination fee was supported. In the 2012/13 season, vaccination coverage in Saga Prefecture was 14.9% whereas the proportion of patients vaccinated was 5.1% among those with clinically diagnosed rotavirus gastroenteritis and 1.9% among those hospitalized for rotavirus gastroenteritis. Thus, vaccine effectiveness was estimated as 69.5% and 88.8%, respectively. This is the first study to evaluate rotavirus vaccination coverage and effectiveness in Japan since vaccination began.