Communicating Human Papillomavirus Vaccine With Japanese Parents and Caregivers With Daughters Aged 12-18

This study will implement an experiment as a sixteen-arm randomized controlled trial in an online survey environment. Before the experiment, participants, who are Japanese caregivers with daughters aged 12-18 who have not received an HPV vaccine, will first answer a pre-experiment survey. The survey will collect information on participants' socio-demographic data and key decision-making factors for HPV vaccine acceptance and confidence. Then, the study will randomly assign the participants to view one digital communication message using a 2 × 2 × 2 × 2 between-person factorial experiment on 'components of message.' The sixteen experimental messages will be developed based on real social media messages posted between November 2021 and April 2022, when the Japanese government prepared to reinstate an active recommendation of HPV vaccines for eligible girls after eight and a half years of suspension.

The sixteen messages will assess four factors: messenger, style, content, and misinformation. Each message will be similar except for one variable in consideration. The messenger component will be whether the message is from an individual or an organization. As individual messengers, the study will set a fictional male or female with common Japanese names who actively communicate about HPV vaccines. As organizational messengers, the study will use the existing accounts of the Ministry of Health, Labour and Welfare or the Japan Cancer Society or a fictional account of an anti-vaccine group. The style component will be whether the message conveys information through storytelling or scientific data. Messages will include personal stories for the storytelling style and statistics for the scientific data style. The content component will be whether the message conveys information about the effectiveness of the HPV vaccine in preventing diseases or the safety of the HPV vaccine. The contents will be built on both factual information and misconceptions about HPV vaccine safety and effectiveness that are often mentioned in the actual social media posts. The misinformation component will be whether the message conveys misinformation or factual information. The study will debrief all respondents exposed to misinformation after the survey.

Lastly, the study will collect data as a post-experiment survey to evaluate how an online message influenced caregivers' trust, confidence, and motivation to vaccinate.

Inclusion criteria

• Female adult caregivers, older than 20, with daughters aged 12-18 who have received none or only one shot of HPV vaccine.

Exclusion criteria

• Caregivers who do not agree to participate in survey, experiment, or both.
• Caregivers with daughters who have already received two or more HPV vaccines.