The primary objective of this survey experiment study is to measure the impact of a mock-up Chinese fact-checking extension on the ability to dispel HPV and HPV vaccine-related misinformation among parents of middle school girls in China.

This survey experiment study aims to assess the feasibility and effectiveness of a mock-up Chinese fact-checking extension on improving the ability to identify HPV and HPV vaccine-related misinformation among parents of middle school girls in three economically diverse regions of China. This includes Shanghai megacity, an urban city in Anhui Province, and rural counties in Anhui Province. The participants will be parents of middle school girls who have not yet received the HPV vaccine. This experiment will randomly assign the participants into intervention or control group. Participants in the intervention group will use a mock-up Chinese fact-checking extension whereas those in control group will not.

The sample size for this study was determined based on the two primary outcomes: knowledge of the HPV vaccine and the ability to dispel misinformation. A review of the existing literature suggests that the intention or confidence among Chinese parents to vaccinate their children with the HPV vaccine, as well as their knowledge about the vaccine and capability to counteract misinformation, typically ranges from 50% to 70%. We assumed a baseline rate of 60% for both vaccine knowledge and misinformation discernment. It is anticipated that exposure to educational interventions will increase these rates by 10%, elevating them to 70%. Using a significance level of 0.05 and a statistical power of 90%, the required sample size was calculated to be a minimum of 473 participants per group. To accommodate potential variability and to strengthen the robustness of the study, 500 participants will be recruited for each group, maintaining a 1:1 ratio. This approach results in a total sample size of 1,000 participants. Such a sample size ensures that the study is sufficiently powered to detect a significant change in the outcomes of interest.

In this study, 11 mobile Weibo post screenshots were created, covering a range of topics including infertility, safety, vaccine ingredients, high-risk cervical cancer types, regular check-ups, transmission routes, and others.

The participants in both groups will complete a questionnaire consisting of six phases:

1. Phase 1 (Baseline Assessment): Participants in both the intervention and control groups will complete a questionnaire covering (a) basic demographic information, (b) HPV vaccine knowledge, (c) HPV vaccine awareness and confidence, and (d) vaccination intentions.
2. Phase 2 (Intervention Module 1): Participants in the intervention group will review six Weibo post screenshots, each featuring a mock-up Chinese fact-checking extension. The control group will view identical screenshots, but without the fact-checking extension. Half of these posts will include false information. After viewing each post, those in the intervention group will evaluate a statement related to the Weibo content and corresponding to one of the predefined (b) HPV vaccine knowledge. Their responses will be: 1) Correct, 2) Incorrect, or 3) I don't know, considering both the post content and the fact-checking extension's findings. Participants in the control group will assess the same statement based only on the post content, with the same response options.
3. Phase 3 (Intervention Module 2): All participants will review four additional Weibo post screenshots, including two containing false information, to evaluate whether exposure to the mock-up fact-checking extension has improved the intervention group's ability to identify false information. The same question format from Intervention Module 1 will be used for responses.
4. Phase 4 (Post-intervention Assessment): All participants are required to fill out sections on (c) HPV vaccine awareness and confidence, and (d) vaccine intentions.
5. Phase 5 (Intervention Module 3): All participants in both groups will be asked whether they use a mock-up fact-checking extension when viewing Weibo post screenshots. If participants choose 'Yes', they will view a Weibo post screenshot with the extension displayed; if they choose 'No', the extension will not be displayed. The same question format from Intervention Module 1 will be used for responses. This phase aims to assess participants' behaviour regarding the use of the extension.
6. Phase 6 (User Experience Assessment): All participants will complete the section (e) the user experience with a mock-up fact-checking extension.

Following the completion of the experiment, a debunking procedure will be conducted for participants in both the intervention and control groups. This is to avoid any potential risks associated with the spread of misinformation on Weibo.

Data analysis will employ Difference-in-Differences (DID) analysis, multiple logistic regression, and other suitable statistical methods to evaluate the effectiveness of the mock-up Chinese fact-checking extension.

Inclusion Criteria:

1. Participants must be parents or legal guardians of female students currently enrolled in participating middle school.
2. The parent's or guardian's female middle school student must not have received the HPV vaccine, must not have an HPV vaccination appointment scheduled, and must not have any contraindications to receiving the HPV vaccine.
3. Participants must be free of mental health disorders or visual/reading disabilities that could prevent their full participation in and completion of the intervention activities.
4. Participants must have provided informed consent and expressed a willingness to actively participate throughout the study.

Exclusion criteria are defined as individuals not meeting the aforementioned inclusion criteria.

Individual participant data that underlie the results reported in the article, after de-identification (text, tables, figures, and appendices), will be shared upon reasonable requests. A written data-sharing request for meta-analysis should be submitted by email with a methodologically sound proposal. Proposals should be directed to zyhou@fudan.edu.cn; to gain access, data requestors will need to sign a data access agreement.

Beginning 12 months and ending 36 months following article publication

Researchers who provide a methodologically sound proposal for meta analysis. Proposals should be directed to zyhou@fudan.edu.cn; to gain access, data requestors will need to sign a data access agreement.