Strategies to Overcome Vaccine Hesitancy: A Systematic Review

"Despite the complexity of vaccine hesitancy and the broad range of its determinants, increasing awareness about benefits of vaccination,...carefully tailored strategies addressing the determinants of the hesitancy can bring about the desired change."

Vaccine hesitancy refers to a delay in acceptance or refusal of vaccination despite availability of vaccination services. Against the backdrop of a large number of unimmunised children globally and frequent outbreaks of vaccine-preventable diseases, this review aims to analyse globally tested interventions to increase vaccination uptake among people with different degrees of vaccine hesitancy.

A search was conducted from June to September 2019 in the PubMed, Global Health, and Science Direct electronic databases to identify peer-reviewed literature on vaccine hesitancy, with no restriction on publication date. The search identified 2,495 peer-reviewed articles in English, of which 33 were included in this review.

The review categorised the interventions described in the literature under four broad themes:

1. Community health training, including: community health information dissemination through health workers, mobilisers, medical officers; social mobilisation - e.g., through medical interns or prominent religious leaders; and knowledge- and experience-sharing by influential women from the community to accelerate vaccine uptake.
   • Most of the interventions analysed in the review fell into this category, as lack of knowledge or awareness about vaccines was observed to be the major cause of vaccine hesitancy. The reviwed studies reported improvement in vaccine uptake after the exercise. Two of them focused on the involvement of mothers for knowledge and experience sharing. Nine studies were based on parent-centred information or education about vaccination and social mobilisation of parents by health workers/medical interns. All these studies showed a significant impact in changing parents' attitude towards their child's vaccination. Messaging on vaccination from political and religious leaders also imparted a positive impact on vaccination uptake. For example, effective communication regarding polio vaccination with the community showed positive impact in Nigeria. However, variation in the study sample with no consideration of population dynamics was a potential limitation of several studies under the community health training theme; one of the studies involved more than 13,000 participants, while another study involved 117 participants.
2. Incentive-based approaches, entailing encouragement of parents to immunise their children through provision of food, other goods, and/or certificates of recognition or monetary support.
   • It was evident from the synthesis that the incentive-based strategies had a positive impact on bringing about vaccination acceptance. The benefit of incentive-based health promotion has always been significant, but sustainability and adherence after intervention is debatable. Furthermore, the implementation of incentives in large populations remains a challenge. At the same time, integration of incentives with other mother and child health services, such as the Janani Suraksha Yojana implemented by the government of India, can bring a positive change in improving immunisation uptake along with education on delivery and nutrition in low-income and low-education settings.
3. Technology-based health literacy efforts, involving use of technology such as mobile phone recall text messages in local languages, pictorial messages, and automated phone calls or interactive voice recordings to spread awareness.
   • Educational videos, lectures in hospital settings, mobile vaccination team visits, social marketing, and web-based questionnaires have been used to bring about behavioural change regarding vaccination. In Northern Nigeria, a relative increase of approximately 310% in the polio vaccination uptake was observed through an educational intervention with a video containing awareness message about polio vaccination. Although recall strategies showed improvement in vaccine uptake by addressing the issues of vaccine hesitancy, they were inconsistent in all studies. Therefore, passive reminders sent through modern communication channels may be only effective in case of technology-friendly populations.
4. Media engagement, including mobilisation through various campaigns and platforms such as radio, TV, and print media - ideally featuring concise, easily understood public service announcements by national public figures, well-known and authoritative local representatives, and representative members of the intended population.
   • In conjunction with awareness-creating strategies, use of mass media in various forms such as print, audio, television, and social media can stimulate a positive perception among the population in different settings. However, improper documentation and socio-economic disparity in demographics are the major downsides in the health literacy using a media-based intervention strategy.

Of the 33 studies, 29 were at a high risk of bias, and only one study had no risk of bias. Thus, the researchers call for more studies on vaccine hesitancy with better study design, as well as those covering specific populations.

In conclusion: "This study indicates that the strategies should be based on the need and reasons for vaccine hesitancy for the targeted population. A multidimensional approach involving community members, families, and individuals is required to address this challenging issue."