Understanding barriers to immunization among women with zero-dose or under-immunized children in an urban area in Cameroon.

Background: Zero-dose children represent a major public health challenge in low-income countries. In 2024, the Nkolndongo Health District in Yaoundé, Cameroon, recorded the highest number of zero-dose children in the country, according to the District Health Information Software 2 (DHIS2) data. Objective: This study aimed to identify and describe the main reasons for non-vaccination and the obstacles to vaccination among zero-dose and under-immunized children in the Ndolndongo Health District, Yaoundé. Methods: A cross-sectional study was conducted from December 2024 to July 2025. The study used a convergent parallel mixed-methods design across three purposively selected priority health areas of the Nkolndongo Health District in Yaoundé (Nkolo, Essomba, Mimboman 2). Under-immunized children were defined as those who had missed at least one scheduled vaccine dose at the time of the study. This study included 50 women with zero-dose or under-immunized children, identified by community health workers or leaders of women's associations, through consecutive, non-exhaustive sampling. Vaccination status was verified using vaccination cards and health facility registrars. Data collection included both quantitative (questionnaires) and qualitative (focus groups and interviews). The qualitative analysis was conducted using NVivo and Atlas.ti, with thematic analysis and grounded theory principles, while the quantitative analysis was conducted using SPSS version 26.0. Results: Twenty-three percent (23%) of children were classified as zero-dose. Mothers were predominantly single (74%), had secondary education (70%), and lived in poverty (66% had less than 50,000 Central African CFA francs, FCFA, per month). The most frequent reasons for non-vaccination were forgetting appointments (23%) and previous experience of adverse events following immunization (19%). Qualitative analysis revealed multiple barriers, including vaccine safety concerns, negative impacts of the coronavirus disease 2019 (COVID-19) pandemic, social media misinformation, inadequate sensitization, emotional factors, sociocultural beliefs, health service dysfunction, and logistical constraints. Conclusion: Within this study population, zero-dose children require multifaceted interventions targeting misinformation, strengthening health systems, adapting services to mothers' constraints, and engaging entire communities, including male partners and vulnerable populations.