Association between administration or recommendation of the human papillomavirus vaccine and primary care physicians' knowledge about vaccination during proactive recommendation suspension: a nationwide cross-sectional study in Japan.

Objective: The Japanese government suspended the proactive recommendation of the human papillomavirus vaccine (HPVv) in 2013, and the vaccination rate of HPVv declined to <1% during 2014-2015. Previous studies have shown that the recommendation by a physician affects a recipient's decision to receive a vaccine, and physicians' accurate knowledge about vaccination is important to increase vaccine administration. This study aimed to evaluate the association between physicians' knowledge of vaccination and the administration or recommendation of HPVv by primary care physicians (PCPs) in the absence of proactive recommendations from the Japanese government.

Design: Cross-sectional study analysed data obtained through a web-based, self-administered questionnaire survey.

Setting: The questionnaire was distributed to Japan Primary Care Association (JPCA) members.

Participants: JPCA members who were physicians and on the official JPCA mailing list (n=5395) were included.

Primary And Secondary Outcome Measures: The primary and secondary outcomes were the administration and recommendation of HPVv, respectively, by PCPs. The association between PCPs' knowledge regarding vaccination and each outcome was determined based on their background and vaccination quiz scores and a logistic regression analysis to estimate the adjusted ORs (AORs).

Results: We received responses from 1084 PCPs and included 981 of them in the analysis. PCPs with a higher score on the vaccination quiz were significantly more likely to administer the HPVv for routine and voluntary vaccination (AOR 2.28, 95% CI 1.58 to 3.28; AOR 2.71, 95% CI 1.81 to 4.04, respectively) and recommend the HPVv for routine and voluntary vaccination than PCPs with a lower score (AOR 2.17, 95% CI 1.62 to 2.92; AOR 1.88, 95% CI 1.32 to 2.67, respectively).

Conclusions: These results suggest that providing accurate knowledge regarding vaccination to PCPs may improve their administration and recommendation of HPVv, even in the absence of active government recommendations.