The goal of this clinical trial is to examine in the parental HPV knowledge and attitude, and their children's completion rates in Indonesia. The main question[s] it aims to answer are:

• Is the digital educational intervention in improving parent's HPV knowledge in the intervention group compared to the control group?
• Is the digital educational intervention in improving parent's attitude toward HPV vaccine in the intervention group compared to the control group?
• Is the digital educational intervention more effective in increasing children's HPV vaccine completion rates in the intervention group compared to the control group?

Participants in intervention group will:

• watch a 8 minutes video in front of class at once.
• after video education intervention, in 2 weeks, participants received 2 reminder messages before first and second vaccination event, respectively.

Participants in control group will:

• Receive usual announcement regarding vaccine by staff

Research process started after obtaining permission principal of the elementary school and primary health centre. Because the target population was parents of girls in the 5-6th level, permission was required from the elementary schools. Meanwhile, another permission must be obtained from the Primary Health Centre, they have authority to administer the HPV vaccine to children at the school.

All participants (parents) were recruited from 10 elementary schools. The schools were divided into 2 arm (e.g., Digital education group, Usual information service group) by cluster randomizing. The group allocation were concealed from the participants, elementary teachers and primary health centre. Participants were unaware of the existence of any other group than the one they received. According to sample size calculations, the number of adequate sample sizes in this study based on sample size calculation results at the completion rate. The dropout rate estimation of 10% according to a previous study by Reiter (2022), the total sample size increased to 269 + (10% x 269) = 296 participants.

The researchers got an approval from schools to invite parents to attend the school of event invitations. Each participant came to the school where their child attended. Parents attended the regular meeting on the appointed day. Frequently, event invitations have become a routine program in elementary school. It was a routine agenda to socialize interesting programs related to students and parents. In parallel with the above, the research team coordinated with the Primary Health Center as the administrator of the HPV vaccine in elementary schools. Thus, the research team determined the time to give the digital education intervention and the follow-up evaluation.

During the process, the researchers approached potential participants and explain to them the purpose of this study, participant rights, risks, and benefits. Then potential participants were asked to sign in the informed consent form with serial numbel. The outcome measurement questionnaires were distributed to the participants, either the intervention group or the control group.

At baseline, the eligible participants were asked to fill out the questionnaires. After complete, a 8 minutes video was played in front of class. Then, the participants took a post-test right after the intervention finish their meeting and in the control group as well. The post-test assessed HPV knowledge and attitudes toward the HPV vaccine. Prior vaccination events, the reminder messages were sent to parent's mobile phone. At this stage, the researcher observed the first dose of HPV vaccine uptake among female students during the HPV vaccine administration program at school. The researcher collected data by observing female students who received the first and second doses of HPV vaccine at the vaccination event, then confirmed the researcher's observations with the Primary Health Center record. All data was recapitulated and stored in excel format. Data was kept by the researcher to maintain confidentiality. All data analyses were performed using SPSS software from IBM Corp.

Statistical analyses, below:

1. Pearson Chi-Square test or Fisher's exact test was used to analyse the HPV vaccine completion rate between groups.
2. The T-test was used to analyse the HPV knowledge and attitude towards HPV vaccine between groups;
3. ANCOVA analysed the intervention efficacy on knowledge, attitude, and HPV vaccine completion rate between two groups.

Inclusion Criteria:

• Parents over 17 years old
• Parents Parents who have daughters of 5-6th level in elementary school
• Parents live with their children in one house
• Parents have a mobile phone with WhatsApp application capabilities
• Parents who have their daughters have been enrolled in School-Based Immunization Program database
• Parents able to communicate fluently in Bahasa Indonesia
• Parents agree to review their child's medical record of vaccination

Exclusion Criteria:

• Parents have diagnosed with mental, visual, and hearing impairment/problems diagnosed by doctors
• Parents whose children have been HPV vaccinated
• Parents whose children are over 14 years old
• Children who have a history of allergies and/or side effects in previous vaccination programs

due to confidentiality protocols, participant data cannot be shared.