JMIR Publications

ABSTRACT

Background:

In Japan, the human papillomavirus (HPV) vaccination rate has dropped to nearly zero since the suspension of proactive government recommendations in 2013. Following the termination of vaccination suspension in 2021 and subsequent proactive vaccination recommendation in 2022, it is crucial to promote catch-up vaccinations for those who missed their initial opportunity.

Objective:

This trial aims to evaluate the effect of video-based informational intervention on the uptake of catch-up HPV vaccinations among unvaccinated young adult women in Japan.

Methods:

In this randomized, parallel, single-blinded, internet-based trial, we recruited women aged 18–26 years unvaccinated for HPV through an online research panel. The participants were randomly assigned (1:1) to receive either an educational leaflet containing information on the HPV vaccine and a short narrative video (intervention) or the leaflet alone (control). The primary outcome was the difference in proportion between both groups regarding the uptake of the free catch-up vaccinations at the follow-up survey after 3 months.

Results:

We enrolled 4065 women in the trial and randomly assigned them to either the intervention (2274 women) or the control (2331 women) group. Of these, we excluded 2595 women (63.8%) who did not respond to the follow-up survey, resulting in 1017 and 993 women in the intervention and control groups, respectively, for the final analysis. At the 3-month follow-up, 11.3% (228/2010) of the participants received at least one catch-up vaccine dose. The intervention and control groups had 10.5% (107/1017) and 12.2% (121/993) uptake, respectively. The difference in proportions between both groups was -1.7% (95% confidence interval [CI]: -4.5–1.2%), and the adjusted difference was -1.6% (95% CI: -4.3–1.0%). In the subgroup analysis, the intervention group had a lower proportion of catch-up vaccination among sexually experienced women who had prior sexual intercourse experience (difference in proportion: -5%, 95% CI: -10% to -1%) and those who had undergone a Pap test within the past 2 years (difference in proportion: -11%, 95% CI: -20% to -1%). Women with lower educational levels had lower vaccination rates compared to those with higher educational levels (difference in proportion: -7%, 95% CI: -10% to -4%). In addition, women who had undergone a Pap test within the past two years had higher vaccination rates compared to those who had not.

Conclusions:

Our study demonstrated that video-based interventions did not have a substantial impact on the uptake of catch-up HPV vaccinations among young adults. It is desirable to explore effective interventions in real-world settings to remove the barriers to vaccination. Clinical Trial: Japan Registry of Clinical Trials jRCT1030230315; https://jrct.niph.go.jp/en-latest-detail/jRCT1030230315