Do Peer-based Education Interventions Effectively Improve Vaccination Acceptance? A Systematic Review

"The research that exists illustrates the promise of this approach for certain vaccines and populations."

Evidence suggests that vaccination uptake and positive vaccination beliefs can be bolstered by multicomponent, dialogue-based approaches. Peer-based education interventions, in which peers lead by example and act as vaccine ambassadors, are one such strategy. This systematic review aims to consolidate the quantitative evidence surrounding the effectiveness and experience of peer-based education initiatives to improve vaccination beliefs and behaviours.

The researchers conducted searches of Web of Science and PubMed between April and June 2022, and then again in June 2023. The inclusion criteria encompassed using peers (individuals with key shared characteristics, circumstances, or experiences, but without professional training), being education based, and being an intervention that addresses vaccination beliefs and behaviours (e.g., vaccination uptake). Systematic screening revealed 16 articles. The various study methods utilised in the articles were surveys (seven), randomised control trials (six), population vaccination rates (two), and mixed methods with surveys and interviews (one). Five of them measured a change in vaccination rate, four collected vaccination uptake rates, three gathered data on willingness to vaccinate, three surveyed the knowledge and beliefs of participants, and one assessed the satisfaction with the intervention.

Overall, 13 of 16 studies reported a positive impact of the peer intervention. The different intervention strategies used were grouped into the following:

• A quick chat with a peer: These interventions involved peer education tables or promotions, having peers provide information and support during an immunisation clinic, and peer phone calls to unvaccinated individuals. Even though this was the least intensive intervention strategy, five studies had a positive impact on vaccination, with increased vaccination rates compared with baselines.
• A workshop/lecture by peers to provide information on vaccination: These interventions mostly involved a peer training by public health professionals and then an educational session. All but one of these types of studies had a positive impact on either knowledge and beliefs or willingness to vaccinate.
• A narrative-onetime approach: All three studies that involved peer-based messaging provided online and assessed the impact on willingness to vaccinate had a positive impact.
• Repeated contact with a peer: One such study involved a two-month-long programing among senior citizens, and one assessed a peer-led Facebook group among essential workers. Both studies found an increase in vaccination uptake or interest in vaccination information.

In terms of vaccine uptake specifically, nine studies showed improvements in the uptake of vaccines. For example, in an intervention at a senior living centre, the immunisation rates for influenza and pneumococcal rose by a greater percentage for those in the intervention building than the control over the two years. Similarly, a narrative intervention to improve human papillomavirus (HPV) knowledge and vaccination in college-aged women found that a combined peer and health expert intervention had a nearly double rate of HPV vaccination at two months compared with the control. In a study that utilised peer ambassadors at same-day COVID-19 vaccination clinics, 197 more individuals were vaccinated at centres with peers compared with those without peers.

Notably, the peer-based interventions show a generally positive effect on vaccine uptake and beliefs, but apart from one paper - on the Diné (Navajo) population which is known to be vaccinate hesitant rooted in governmental mistrust - there was no research on the effectiveness of peer-based educational interventions in communities that present low levels of vaccine confidence. This observation suggests that there is limited evidence for the use of peer-based interventions to address vaccine hesitancy, which is rooted in specific communities - for example, migrant communities, anthroposophic or religious communities, or online communities.

Thus, despite reported positive effects of using peer-education based initiatives to improve vaccine uptake and beliefs, this systematic review reveals that there is limited existing research in support of this strategy. The strategies that initially appear the most effective are those with a combined peer and health-expert approach, those that have more group-specific/targeted interventions, and those that use a long-term, repeated approach. More research is needed to confirm these results and to assess the effectiveness of a peer-based education intervention in a wider variety of settings and for other vaccine types.

In conclusion: "Implementing vaccine education by peers could help to address socio-cultural barriers through a culturally competent addition to traditional vaccine interventions. Whilst the claim of the value of peer-based education system continues to be made in the literature, more solid evidence on best approaches is needed."