Factors associated between behavior of administrating or recommending mumps vaccine and primary care physicians' knowledge about vaccination: A nationwide cross-sectional study in Japan.

Background: In Japan, the mumps-containing vaccine was withdrawn from routine vaccination in 1993, and it became a voluntary vaccination. This study aimed to evaluate the association between the physicians' knowledge about vaccinations and the administration or recommendation of the mumps vaccine.

Methods: We conducted a nationwide cross-sectional study targeting primary care physicians (PCPs) in Japan. We used a web-based self-administered questionnaire by Preventive Medicine and Health Promotion Committee Vaccine Team, the Japan Primary Care Association (JPCA), from March to June in 2019. The outcome of the study was the association between PCPs' knowledge about vaccine and the administration or recommendation of mumps vaccine. We obtained the information on background, subsidies of mumps vaccination for children from the local government, and vaccination quiz scores. We performed logistic regression analysis to estimate the odds ratios (ORs) and 95% confidence intervals (CIs).

Results: Among 10,470 PCPs in JPCA, 5075 were excluded. We received responses from 1084 PCPs (20.1%) and enrolled 981 participants in the analysis. PCPs with a higher score on the vaccination quizzes were significantly more likely to administrate the mumps vaccine for adults (adjusted odds ratio [AOR] 1.93, 95% CI 1.45-2.59, < 0.001) and recommend mumps vaccine to adults than PCPs with a lower score (AOR 1.78, 95% CI 1.33-2.40, < 0.001).

Conclusions: We revealed an association between the administration or recommendation of mumps vaccine and PCPs' better vaccination knowledge.