Countering Vaccine Hesitancy: A Systematic Review of Interventions to Strengthen Healthcare Professionals' Action

"[K]eeping examining which methods could be the most effective is crucial[,] as there is an association between recommendation by HCPs and vaccination[,]... and the doctor–patient relationship represents a key for building trust..."



Vaccine hesitancy is a complex phenomenon that encompasses the concepts of indecision, uncertainty, delay, and reluctance. The VAX-TRUST project examines vaccine hesitancy as a broad societal phenomenon. To support VAX-TRUST, this systematic review aimed to identify interventions designed for healthcare professionals (HCPs) to address hesitancy and increase vaccine uptake, looking for possible innovative tools.



Articles were eligible if evaluated interventions explicitly intended for HCPs/healthcare students. The search was run on January 26 2022. There were no geographical limits, but only articles published in 2016 or after were included. A total of 17,492 records were identified; 139 articles were selected.



Over half had a pre-post design without a control group (n = 78), followed by cluster randomised controlled trials (RCTs) (n = 20), non-randomised controlled trials (n = 16), interventional studies with only post-intervention evaluation (n = 16), qualitative studies (n = 7), and RCTs (n = 2). In the case of controlled trials, no intervention/usual care was the most frequent control group (n = 18).



Forty-one articles focused on single-component interventions, 60 on multi-component interventions involving only HCPs and/or students, and 38 on multi-component interventions involving also other professionals. Main components were in-person education (n = 76), synchronous (n = 10) and asynchronous (n = 23) online learning, educational materials (n = 26), performance assessment and feedback (n = 33), electronic health record (EHR) changes (n = 30), role play/simulation (n = 21), and online games/apps (n = 5). Educational sessions were mainly about scientific update or communication. A summary of the main findings of each intervention is provided in the section "Details on the main results of the intervention evaluation" of Supplementary file S2.



Outcomes of interventions were grouped in terms of: vaccination rates (n = 69), knowledge (n = 32), attitudes (n = 26), confidence in counselling (n = 30), and acceptability (n = 16). Sample findings:

• Asynchronous learning was on both scientific updating and communication (n = 4). The most frequent outcome was confidence (n = 4), showing promising results. Similar results were reported for knowledge and attitudes (n = 3).
• Among digital tools, one virtual reality game with scenario simulations showed a significant reduction in vaccination refusal among participants' patients. One serious game and one chatbot-based learning approach significantly improved knowledge.
• Interventions addressed to HCPs through EHR modifications were frequent (n = 8). The effect on vaccination rates was mixed.
• 12 interventions included assessment and feedback, matched with in-person sessions (n = 5), online learning (n = 5), educational material (n = 1), or incentives (n = 1). One intervention focused on motivational interviewing. Four evaluations reported significant improvements in vaccination rates, while most results were mixed or non-significant (n = 6).
• Considering other combinations, asynchronous learning was paired with smartphone app based on evidence-based recommendations or with an exercise in which students managed a primary prevention intervention, showing significant improvement in knowledge, attitudes, or self-efficacy. In-person session was utilised alongside practicing muscular injections, reporting significant improvement in knowledge, attitudes, and confidence. Lastly, one intervention integrated videos showcasing interactions with patients and a writing exercise in which students responded as physicians.
• 5 interventions were mainly composed of EHR changes and in-person HCP education, combined with patients/parents' actions or organisational interventions. All interventions reported a significant vaccination rate increase, except for an intervention not including a component addressed to patients.
• 8 interventions included assessment and feedback along with in-person HCP education, educational material, or asynchronous learning, all combined with actions for patients/parents. One intervention focused on motivational interviewing. Overall, the vaccination rates improved. One intervention reported significant improvement in attitudes and comfort in counselling.
• One intervention combined an app supporting HCPs in identification of children who missed vaccinations and organisation of scheduling with actions addressed to parents, finding encouraging qualitative results.

Reflecting on the findings, the researchers note that, frequently, interventions were multi-component strategies and/or combined with actions for patients. Many works highlighted the most effective interventions to increase vaccination rates were those directly geared toward the population who should get vaccinated and those consisting of multiple strategies.



This review showed most intervention categories had mixed findings, showing both significant and non-significant results, especially if more outcomes were measured within one domain. No categories showed completely non-significant results across all outcomes, but very few had consistently significant positive results. That said, all interventions combining role play/simulation with in-person education showed significant improvement in knowledge, attitudes/perceptions, or confidence; the same was not true for role play/simulation plus asynchronous learning. These findings highlight the importance of simulation as tool for supporting HCPs and suggests a possible superiority of the in-person education that should be investigated.



Within educational sessions, the topic of communication was almost as frequent as scientific update. Communication importance was also highlighted by the simulation components of many interventions, which were mainly aimed to test communication skills. "Thus, including communication training in interventions to increase vaccine uptake is essential. However, the effectiveness of communication approaches depends on the message-framing techniques used....Unfortunately, most articles did not provide details on the contents of the communication training, so future research should delve into the characteristics of the programs to understand if the non-significant results could be partially due to the taught communication methods."



This review highlighted the need of delving into communication strategies and using more robust evaluations, longer follow-up and standardized measurements.