Supplemental Strategies to Reach Zero-dose Children: Scoping Review

"New approaches are being sought to improve reach to the highest priority populations for vaccination and/or improve the use of resources employed during vaccination programs."

This scoping review, published by the Johns Hopkins Bloomberg School of Public Health, seeks to capture and describe the breadth of strategies that could serve as alternatives to national, non-selective supplemental immunisation activities (SIAs) for measles vaccines and other Expanded Programme on Immunization (EPI) components. In particular, the review's objective is to assess what supplemental strategies have been used to reach zero-dose/unvaccinated or under-vaccinated children in low- and middle-income countries (LMICs) and to understand how these strategies were used and tailored to populations of interest. The results are intended to inform future data collection and programme and policy decisions amongst decision makers to understand what is needed for countries to move away from nationwide non-selective SIAs.

As explained in the report, "There is certainly a critical role for national, non-selective SIAs in specific settings and contexts. However, as global immunization evolves, there is a need to equip global partners and countries to consider alternatives that diverge from the traditional nationwide, non-selective campaign - an inherently resource-intensive and at times redundant approach - to maximize impact while minimizing resource demands." These do not seek to vaccinate all eligible children nationwide but instead focus on vaccinating zero-dose children, which for the purposes of this review are defined as those who have never received a single dose of any vaccine. "Understanding the success, extent, and scope of these strategies implemented is instrumental in developing more efficient, effective vaccination strategies to fill immunity gaps."

The review was limited to literature describing: interventions for measles-rubella vaccination, polio vaccination, and those addressing the EPI as a whole; interventions that focus on the "reach" component of the Identify-Reach-Measure-Monitor-Advocacy (IRMMA) framework (developed by Gavi to help countries adopt a structured approach to reach zero-dose children and missed communities); and interventions in low-income or lower-middle-income countries. A total of 190 articles were included in the final analytic set. Based on the IRMMA framework, the supplemental strategies were classified into four categories: demand generation, human resources, supply chain, and service delivery. The results of the review are discussed according to these categories. In brief, the following are some of the findings:  

Demand generation: Demand-side interventions included financial incentives for beneficiaries, reminders and recall for caregivers when vaccinations are due, and information, education, and communication (IEC) interventions to provide information to caregivers. Of the 46 articles identified, more than half included reminders and recall systems. Providing information and education to caregivers was the intervention that seemed successful in all contexts. The report also discusses social mobilisation as part of demand generation. There were 51 articles identified that included social mobilisation interventions, all of which seem to work in all contexts. Social mobilisation is considered a key aspect of immunisation programmes and included programmes that involve engaging male caregivers and religious leaders and community mobilisers (such as town announcers and development committees).

Human resources: Human resource interventions included healthcare worker training, supportive supervision, and financial incentives for healthcare workers. Of the 40 articles identified, more than half included training and supportive supervision, which seemed successful in all contexts.

Supply chain: Interventions focused on supply chains included the implementation of new vial policies, improved cold chain equipment availability, and changes in vaccine distribution.

Service delivery: The scoping review found the highest number of articles and interventions in this category. Within service delivery, interventions were classified as "planning" interventions when the focus was on identifying children and tied to vaccinating them, "integrating" when tied to another government department (education, transportation), and "tailoring" when traditional immunisation was adapted to reach un- or under-vaccinated children. Planning interventions included Reaching Every District/Reaching Every Child (RED/REC), microplanning, community immunisation points, and the leveraging of community health workers to vaccinate children. Integrating included using immunisation registries, defaulter tracing, and calendars to plan immunisation sessions. Tailoring included innovations such as Periodic Intensification of Routine Immunization (PIRI), child health days/weeks, outreach sessions, and extended clinic hours.

The report notes that selecting which supplemental strategies to implement - and how effective different strategies are in improving immunisation coverage - is heavily context specific. Overall, the report notes that "the range of strategies captured in this review highlights the breadth of possibilities for countries aiming to shift from broad, non-selective campaigns to more targeted - arguably, more sustainable - approaches integrated into the routine EPI. In focusing on these routine enhancements, we are challenged to capture intervention-specific impact and quantify the effect of these approaches on immunization coverage, timeliness, and trust. Few studies were able to disentangle the effects of a specific approach on target outcomes or capture individual data showing the effect on those exposed to the intervention. Many relied on DHS [Demographic and Health Surveys] or other national or subnational surveys to associate interventions with changes in population-level coverage, which falls short of describing local effects in the communities experiencing higher levels of under- or unvaccinated children."

Nevertheless, several strategies described in the report have been implemented in multiple countries, and some demonstrate greater potential to replace nationwide non-selective campaigns. The report therefore highlights the following:

Demand generation
 

• Reminders and recall systems and community mobilisers have been used in many different countries and settings, and they seem to be positively impacting vaccination coverage where they are implemented.

Service delivery
 

• Tailoring through community immunisation points at schools and transit points, outreach sessions, and extended hours could expand more opportunities for reaching un- and under-vaccinated children.
• Supporting and amplifying RED/REC and microplanning could help bridge implementation barriers and facilitate targeted, tailored strategies through enhanced planning.

Cross-cutting
 

• Strategic funding could help expand and enhance service delivery and demand generation and could help stem the need for vaccination campaigns.
• Integrating multiple components and tailoring to the appropriate local context offers an opportunity to maximise reach and impact.
• Evaluating which strategies are most effective in which contexts and understanding how decision makers, health workers, and caregivers perceive these interventions are key areas needing further research.