Background
The COVID-19 pandemic disrupted essential health services, including routine immunization, contributing to the accumulation of millions of children missing life-saving vaccines. Pandemic impacts, combined with persistent challenges faced by low- and middle-income countries in reaching all eligible children for vaccination, resulted in increasing zero-dose and underimmunized populations, widening immunity gaps and increasing the risk of outbreaks of vaccine-preventable diseases such as measles, polio, and diphtheria.
The Big Catch-up (BCU) is a global initiative launched in 2023 by the World Health Organization (WHO), the United Nations Children’s Fund (UNICEF) and Gavi the Vaccine Alliance (Gavi), with the aim of reaching children who have missed their vaccines, restoring coverage to previous levels, and strengthening immunization systems.
As a time-bound initiative, the BCU garnered focused attention, and in many settings additional resources, to close equity and coverage gaps. Going forward, reaching children who miss vaccine doses for any reason remains an essential feature of a well-functioning and equitable immunization program. With a shifting financial future for immunization programming, integration of immunization services into regular primary care and health systems functions becomes even more critical. Ensuring that children are reached on time with scheduled vaccines while at the same time deploying catch-up activities effectively into routine immunization to reach anyone who is missed is the complex challenge ahead.
The BCU catalyzed programmatic change across diverse settings – in many cases, setting the stage for institutionalization of catch-up efforts. While countries and partners have implemented a wide range of strategies to recover coverage, there is an urgent need to systematically document lessons learned, evaluate the effectiveness of interventions, and share best practices to inform future efforts. This is an important moment to share evidence on what was achieved, how it was implemented, and which lessons can inform current and future immunization strategies.
Aims and scope of the collection
The purpose of this collection is to provide a comprehensive body of evidence and programmatic insights on the design, implementation, and outcomes of the BCU across diverse settings that will support countries and global stakeholders in accelerating immunization recovery and building more resilient systems that consistently reach children on time, on schedule wherever they are.
Topics of Interest
We welcome submissions exploring the intersection between the BCU’s core objectives and broader immunization and health systems:
- Reaching zero-dose children: identification, mapping, and tailored approaches to underserved communities
- Catch-up vaccination strategies: planning, execution, and outcomes of campaigns and intensified routine immunization
- System recovery and integration: strengthening service delivery, workforce and supply chains, linking immunization with other primary health care interventions
- Community engagement and demand generation: addressing vaccine hesitancy and improving uptake
- Data systems and digital innovations: use of data for targeting, monitoring and decision-making, strengthening disease surveillance
- Financing, institutionalization and sustainability: resource mobilization, institutionalization of system changes and long-term program sustainability
This Collection supports and amplifies research related to SDG 3, Good Health and Well-Being.
All submissions in this Collection undergo the journal’s standard peer review process. Similarly, all manuscripts authored by a Guest Editor(s) will be handled by the Editor-in-Chief. As an open-access publication, this journal levies an article processing fee. For more information on publication fees, please see here. We recognize that many key stakeholders may not have access to such resources and are committed to supporting participation in this issue wherever resources are a barrier. For more information about what support may be available, please visit OA funding and support, or email [email protected] or the Editor-in-Chief.
This call for submissions is available online here.
