How Has Co-design Been Used to Address Vaccine Hesitancy Globally? A Systematic Review

"Co-design is a prominent strategy to support the development of interventions to address vaccine hesitancy."

Because reasons for vaccine hesitancy are multifactorial, one recommended approach is to tailor interventions to the specific contextual setting and to develop them in collaboration with the community. This systematic review aimed to synthesise the literature on how co-design - that is, the meaningful involvement of the end-user in the research process - has been used to reduce vaccine hesitancy and increase vaccine confidence around the world.

In March and October 2024, the researchers searched six databases for empirical articles published in peer-reviewed journals. Some of the key search terms included 'vaccines', 'immunization', 'trust', 'community participation', and 'co design'. Any type of childhood or adult vaccine could be the subject of the study. Table 1 in the paper provides an overview of the 27 included studies, summarising the study location (spanning 14 countries), vaccine of interest, aim, type of co-designed intervention, and co-design collaborators. A note on the latter category: Groups repeatedly mentioned as co-design collaborators were children and youth, parents and guardians, healthcare workers, and community leaders. Many studies focused on working with underserved populations, including residents of informal settlements, youth experiencing homelessness, migrants and refugees, indigenous communities, and ethnic minority groups.

The included studies utilised a variety of frameworks to guide the co-design process and select the data collection methods. Eight studies drew on principles from community-based participatory research (CBPR) and participatory action research (PAR), while four studies adopted the design thinking approach. Apart from that, the Theory of Reasoned Action, Health Belief Model, Behavior Change Wheel, and Theory of Planned Behavior were used. In addition, two studies used inoculation theory, which exposes people to weakened forms of misinformation in order to build resilience against it. In line with the respective frameworks, co-design was typically described as a process occurring in several phases, and it was common for different collaborators to be involved at different stages. 

The co-design processes described produced a diverse range of interventions, with the majority being either entirely digital or including a digital component. Formats ranged from videos to apps, text or audio messages, websites, and digital toolkits. Videos were the most common and were either educational or narrative, featuring relatable stories of influential community members. The two studies with entirely non-digital interventions developed theatre performances and community-led workshops and posters. It was common for interventions to have multiple components.

Even though all studies dealt with vaccine confidence or hesitancy, the intended outcomes varied. For example, for some interventions, success was defined as improvements in vaccination-related knowledge and attitudes, while for others, it was defined as an increase in immunisation rates, greater resilience to misinformation, or impressions and engagement with the intervention. Two included studies tested their interventions through randomised controlled trials (RCTs). One of the RCTs reported that vaccine-hesitant caregivers had significantly improved attitudes toward childhood vaccinations after watching a co-designed animation compared with controls. The second RCT found no sustained difference in receipt of, or intention to receive, the flu vaccine between the group who watched co-designed animated videos and the control group.

When reflecting on the co-design process, the authors of the included studies repeatedly mentioned that establishing mutual trust between researchers and co-design collaborators was vital. This goal was achieved by, for example, delaying data collection and first dedicating some time to observation, building rapport with the intended community, or engaging with community leaders or other influential community members. Other recommended strategies included accommodating collaborators' needs when it comes to arranging co-design sessions, and showing empathy toward collaborators' concerns before trying to address them. Some noticed that co-design had a positive impact on community ties and empowerment, as well as people's general interest in taking care of their health, thereby providing benefits beyond the scope of the designed intervention.

Several challenges and limitations of co-design were also noted, the most prominent one being a lack of generalisability of findings beyond the study context. This issue often stemmed from uncertainty that co-design collaborators were truly representative of the population for whom the intervention was being designed. Another potential source of friction in co-design was power imbalances. It was important to ensure that a handful of individuals were not dominating the discussions and that the researchers avoided a paternalistic approach and remained open to feedback. Another challenge some authors reflected on was gender imbalances during recruitment. 

Most studies included in this review were published in the last 4 years, indicating that co-design is a relatively new strategy for building vaccine confidence. Therefore, the researchers are not surprised that many co-designed interventions have not yet been tested and that effectiveness data seem to be pending. However, they argue, the increased utilisation of co-design in public health necessitates a deeper investigation of its effectiveness. The researchers provide additional recommendations for future research. For instance, insights into co-design practices for reducing vaccine hesitancy in low- and middle-income countries are currently lacking but are vital.

In conclusion: "Although co-design might empower research participants and help address the specific concerns of hesitant individuals, and thus make interventions for reducing hesitancy more effective, the data to corroborate this is still emerging."