Effect of a Brief Web-Based Educational Intervention on Willingness to Consider Human Papillomavirus Vaccination for Children in Japan: Randomized Controlled Trial

"Vaccine awareness programs are necessary, and campaigns through the media and social network services can play significant roles..."

The human papillomavirus (HPV) vaccination rate in Japan has fallen to nearly zero since the suspension of governmental proactive recommendations in 2013, owing to the development of purported adverse events. These cases were reported repeatedly in Japanese media in sensational ways. As a result of the dissemination of misinformation and the misunderstanding of the HPV vaccine, most Japanese people have distrust toward the HPV vaccine. This randomised controlled trial (RCT) aimed to evaluate the effects of a brief web-based educational intervention using the theory of behavioural insights (BI) on the willingness of adults to consider the HPV vaccine for their daughters and sons.

In this study, the researchers created a one-page BI-based material featuring three sentences (see above), which were deemed to be in line with scientific evidence and objective facts associated with the theory of behavioural change and behavioural economics.

1. The first sentence reflects Japanese epidemiological data on cervical cancer (CC), which the HPV vaccine is designed to prevent. With an eye toward behaviour change, the researchers considered the framing effect in crafting this first sentence: In contrast to the sentence they chose, another option - e.g., "2.8% of women diagnosed with cervical cancer die" - might not emphasise the deterioration in health associated with CC. In addition, the sentence they chose applies prospect theory by drawing similarities between the number of deaths due to CC in Japan and fatalities due to traffic accidents.
2. To promote a change in the consciousness of participants, and based on BI research, the presentation of social norms was included as part of the Easy, Attractive, Social, and Timely (EAST) framework in the second sentence of the material.
3. Heuristics (awareness of prejudice and intuition) led the researchers to hypothesise a reduced interest among male participants in the study if they were to focus the BI material exclusively on CC. Therefore, the third sentence conveys that non-CC HPV malignancies are also preventable through HPV vaccination.

To test the intervention incorporating this BI material, the researchers recruited 1,660 participants aged 20 years or older in March 2018 via a Japanese webpage and provided them with a 10-item questionnaire related to the following aspects: awareness regarding HPV infection and vaccination, willingness for immunisation, and actions for prevention. The researchers randomly stratified participants based on sex and age to the intervention group, who received the BI material (digitally) prior to answering the questionnaire, and the control group, who did not have access to this material until after completing the questionnaire.

The study found that only 484 (29.2%) of the respondents were aware of the benefits of HPV vaccination, whereas 543 (32.7%) were aware of the adverse effects. Although only 352 (21.2%) of the respondents displayed a willingness for immunisation of their daughters, there were 40 (4.8%) more respondents in the intervention group with this willingness (adjusted odds ratio [aOR] 1.32, 95% confidence interval [CI] 1.04-1.69).

In an overall comparison between men and women irrespective of intervention, the willingness to consider vaccination for daughters in men was significantly higher than that in women (25.1% vs. 17.3%, P<.001), and the willingness to consider vaccination for sons was also higher in men than in women (20.1% vs 12.8%, P<.001). In a subanalysis, the willingness toward vaccination for daughters in men was significantly higher in the intervention group (aOR 1.46, 95% CI 1.05-2.02). However, such a difference was not observed among women (aOR 1.20, 95% CI 0.83-1.73).

Thus, the findings indicate that providing brief scientific information could increase the willingness to consider HPV vaccination for daughters and sons. A possible reason why the intervention was more effective among men than women is that women may have had more negative attitudes toward HPV vaccination: Overall, 45.7% of women said they know about the adverse events of HPV vaccination, while this rate was 19.8% in men. Such awareness might have influenced the difference in the intervention effect. More study is needed.

In conclusion, this study suggests that "a brief web-based educational intervention increases the willingness of adults to consider the HPV vaccine for their children, especially among men. Thus, providing adequate information to men may be a useful strategy to improve the currently low rates of HPV vaccination."