Reducing zero-dose children and improving routine immunization following COVID-19 through community health workers in...

Routine immunization in Cameroon was severely disrupted by the COVID-19 pandemic, compounding longstanding challenges stemming from sociopolitical instability in the South-West Region. Kumba, hosting large populations of internally displaced persons (IDPs), reported increasing numbers of zero-dose and under-immunized children. This study assessed the effect of training Community Health Workers (CHWs) and Health Care Workers (HCWs) to identify, refer, and link zero-dose and under-vaccinated children to services in Kumba North and South Health Districts. Six low-performing health areas were selected based on routine immunization data. From October 2022 to February 2023, CHWs conducted household visits, identified unvaccinated children, and provided referrals, while HCWs received training on reducing missed opportunities for vaccination (MOV). Monthly supervision and data review supported implementation. Due to large, mobile IDP populations, outcome measures focused on doses administered, not coverage. Costs were estimated using operational expenditures and UNICEF vaccine procurement prices. Penta-1 doses increased from 285 pre-intervention to 3,172, while Penta-3 doses increased from 321 to 2,893. HPV vaccination reached 2,134 adolescents (1,747 girls; 387 boys). CHWs conducted 945 home visits and identified 299 zero-dose children. Operational cost was USD 7,240, and the estimated value of vaccines administered was USD 31,101. Although external factors such as fluctuating conflict intensity or sporadic outreach may have contributed, these were not consistently implemented in the intervention areas. CHW engagement combined with HCW MOV-reduction training substantially increased doses administered in a conflict-affected setting. This low-cost, scalable model can strengthen routine immunization and reduce zero-dose inequities in humanitarian contexts.