Case Study of Big Catch Up (BCU) Immunization Activities in Cameroon
The Big Catch‑Up (BCU) is a global initiative launched by WHO, UNICEF, and Gavi to rapidly close immunity gaps caused by COVID‑19 disruptions. In Cameroon, BCU was implemented through four rounds of periodic intensification of routine immunization between September 2024 and December 2025, across 80 priority health districts, targeting zero‑dose (ZD) and under‑immunized (UI) children aged 12–59 months.
As part of a multi-country BCU research project funded by the Alliance for Health Policy and Systems Research (AHPSR)/WHO, EVIHDAF conducted a BCU case study in Cameroon, in collaboration with the Expanded Program on Immunization (EPI), Ministry of Public Health, from May to December 2025.
Study Objectives
The study was designed to:
- Assess the planning, implementation, successes, and challenges of the Big Catch‑Up (BCU) immunization initiative in Cameroon
- Identify key barriers and facilitators influencing immunization coverage among zero‑dose and under‑immunized children
- Examine financial investments and funding mechanisms supporting routine immunization and catch‑up activities, with a focus on sustainability
Study Methods
Designed as a Mixed-methods case study grounded in the BCU theory of change, we carried out:
Document review
Analysis of 87 documents including national BCU plans, policy documents, SOPs, and reports.
Secondary data
Analysis of routine immunization data (DHIS2) and modeled estimates (IHME).
Primary qualitative data
Key informant interviews (KIIs) and focus group discussions (FGDs) with stakeholders at central, regional, and district levels (Cité Verte, Manoka, Kumba South, and Mokolo).
Primary quantitative data
Household survey of 264 mothers/caregivers of zero-dose or under-immunized children.
Key Results
Primary barriers
Demand‑side drivers like fear of Adverse Event Following Immunization (AEFI), general fear of vaccines, lack of knowledge, and rumors were dominant. Supply‑side failures like stock‑outs, poor planning, and insufficient vials led to 25% of caregivers being turned away. Informal fees and commercialization of vaccines (notably MMR) were reported.
Profile of missed children
Surveyed ZD/UI children averaged 2.5 years: 98.5% were under‑immunized and 1.5% zero‑dose. Caregiver characteristics: 31.4% had no formal education; 41% had started or completed secondary education. Average reported travel time to the nearest health center was 27 minutes.
Dose distribution
The most administered antigens amongst children aged 12-59 months since start of BCU were MMR1, Yellow fever, PENTA1 and Hib1. Administered doses fluctuated between rounds with 34,680 caught-up in Round 1, 25,809 in Round 2, and 31,318 in Round 3. This was primarily because the second round included less than half of the 80 districts covered in rounds 1 and 3.
Geographic heterogeneity
Performance varied markedly by region: the North recorded the highest coverage (81.6%) for 12-59 months children, while North‑West (2.4%), Littoral (7.8%), Centre (8.2%) and West (9%) recorded the lowest.
Systems constraints
Multiple parallel reporting platforms (IASO, DHIS2, ODK, paper) created data fragmentation; documentation by delivery strategy (mobile vs fixed) was insufficient. Heavy reliance on external financing raises sustainability concerns.
Policy Relevance
Cameroon’s 2021 national catch‑up immunization policy provides a strong foundation for institutionalizing BCU strategies within routine services. However, long‑term sustainability remains vulnerable due to heavy reliance on external financing and the high operational costs of flexible outreach strategies in remote and conflict‑affected areas.
Achievements
Across three rounds implemented from September 2024 to March 2025 in 80 priority districts, BCU caught up 91,807 ZD 12-59 months old children. This represents 30.6% of the program’s targeted ZD cohort estimated at 299,654 and 12% of the national ZD backlog estimated at 777,331.
Conclusion
The BCU initiative in Cameroon demonstrated that rapid immunization recovery is possible, but sustaining high coverage requires systemic transformation. While strong central leadership, cascade training, and flexible outreach strategies enabled short-term gains, persistent structural and behavioral barriers continue to undermine routine services.
Through this project, EVIHDAF strengthened national capacity for policy‑oriented implementation research, generating actionable evidence to support equitable immunization recovery, system resilience, and sustainable integration of catch‑up vaccination within routine immunization services in Cameroon.
Snapshot
Study area: Cameroon (Centre, Littoral, South-west and Far-North regions)
Duration: May – December 2025
Partners: EVIHDAF, EPI, MINSANTE
Funder: AHPSR/WHO
A4All Projects
Others Projects
Projects Activities
Publications
Project Outcomes
Publications
No downloads found!
Project Outcomes
Coming Soon ….
Type your paragraph here
