Digital Health Interventions to Improve Adolescent HPV Vaccination: A Systematic Review

"[D]igital health interventions can cost-effectively provide education about HPV vaccination, offer interactive environments to alleviate parental vaccine hesitancy, and ultimately help adolescents engage in HPV vaccine uptake."

Digital health interventions have demonstrated the potential to positively influence parental vaccination decisions and improve vaccine uptake among children. Adolescent human papillomavirus (HPV) vaccination uptake remains suboptimal compared to other vaccines. This systematic review describes and assesses digital health interventions to promote HPV vaccination among adolescents and parents of adolescents and recommends directions for future interventions of this kind.

Using appropriate medical subject headings and keywords, the researchers searched multiple databases and identified 24 studies published in English between January 1 2017 and July 31 2022 for inclusion. Fifteen of the studies were randomised controlled trials (RCTs). The RCT studies included in this review were at relatively low risk for selection and reporting biases, whereas detection bias was the most frequently occurring bias. Most of the studies (18/24, 75%) were conducted in the United States. All but 5 studies were theory informed; the Health Belief Model and the Theory of Planned Behaviour were the most frequently employed theories.

Common features across the interventions studied were dissemination of HPV and HPV vaccine information, tailored feedback or personal stories about vaccinating children against HPV, vaccine reminders, HPV discussion forums or frequently asked questions (FAQ), scheduling assistance or clinic locator, and guidance on how to initiate conversations with children about HPV. The interventions used:

• Text messages (4 studies): Text message reminders to parents of vaccine-eligible adolescents are generally reported as an effective means for their timely uptake of the HPV vaccine, especially regarding vaccine series completion. Educational information in the messages tailored to their stage of decision-making had minimal impact on their adolescents' vaccine series completion. In addition, no significant difference was observed in vaccination rates between motivational text messages emphasising one's susceptibility to HPV and self-regulatory text messages highlighting implementation intentions. However, both types of messages elicited higher vaccination rates compared to the control condition.
• Mobile apps (4 studies): The results were mixed. For example, in one study, vaccine initiation was not found to be significantly greater for parents who used the HPV CancerFree (HPVCF) app compared to those who did not. On the other hand, the rates of HPV vaccination initiation and series completion were 18.8% and 36.8% higher, respectively, among parents who used the Vacteens.org app compared to those in the usual and customary information condition. The app also bolstered parents' positive HPV vaccine beliefs, which was a likely contributing factor for higher levels of vaccine initiation and series completion.
• Social media and websites (8 studies): In two interventions, which were a Facebook campaign to cultivate mother champions of HPV vaccination and a website providing mothers with tailored feedback from virtual assistants, both groups of mothers had significantly increased knowledge about HPV and HPV vaccine. Regarding vaccination behaviour, a Facebook campaign, Health Chat, delivered to mothers was effective, as mothers reported significantly higher initiation of their adolescents' HPV vaccination at 12- (71.3%) and 18-months (73.3%) posttest, compared to baseline (63.4%). Several other interventions exerted negligible effects on vaccination behaviour.
• Digital games (4 studies): For maximal engagement and motivation, these games had features to attract youth primarily by incorporating animated game characters with entertaining storylines.
• Videos (4 studies): Overall, the video-based interventions for parents to improve HPV and HPV vaccine knowledge and intention to vaccinate their adolescents reported positive results.

The interventions generally improved determinants of HPV vaccination, such as HPV-related knowledge, vaccine-related conversations, and vaccination intentions. In particular, text message and social media interventions targeted improved vaccine uptake behaviours, but little meaningful change was observed.

In discussing the findings, the researchers note that several interventions in this review underscored the role of digital technologies as facilitators of effective provider-parent communication and education about HPV vaccination. For maximal effectiveness and safe use of digital interventions, providers' insights about the credibility of these tools are crucial before dissemination to users. Another point raised by this review is that, although the increases in HPV and vaccination knowledge, vaccine-related conversations, and positive vaccination beliefs and intentions associated with digital technologies are likely indications of the decision to vaccinate, they may not be sufficient to cause behaviour change, resulting in an intention-behaviour gap. The researchers suggest that "carefully crafted but succinct, resonating text messages can help parents and adolescents execute concrete action plans that can optimally meet the behavioral goal of HPV vaccination..."

Several studies in this review articulated the importance of gender-neutral HPV vaccination and providing information related to male susceptibility to HPV in the digital interventions to nudge boys to adopt vaccination behaviour. "As part of this transformation, developers of digital interventions for HPV vaccination should consider tailoring design elements and content of the interventions to the gender of users to align with the recommended universal HPV vaccination..." The researchers suggest that this review can serve as a guide for "countries with high digital technology penetration but low awareness of HPV vaccination to develop successful digital interventions for HPV vaccination, which can pave the path to adopt gender-neutral vaccination in the near future."

This review also highlighted the fact that digital interventions for vaccine adherence may not produce positive outcomes if they are implemented for populations of low socioeconomic status. For example, an electronic reminder system with educational messaging about HPV and HPV vaccine did not significantly improve knowledge and vaccination rates among an underserved population, and a social media campaign was not effective among women of low socioeconomic status in initiating vaccine uptake for their adolescents. "These findings reveal a digital divide and the need to consider sub-population circumstances when implementing digital interventions for the controversial issue of HPV vaccination..."