Knowledge, Attitudes, Behavioural and Social Determinants of Childhood Immunisation Among Caregivers and Healthcare Workers in Sierra Leone: A Convergent Mixed-Methods Study

Abstract Background Childhood immunisation remains one of the most effective strategies for preventing vaccine-preventable diseases and reducing under-five mortality. In Sierra Leone, despite progress, subnational disparities, misinformation, and health system barriers continue to contribute to under-immunisation and zero-dose children. This study assessed caregivers’ knowledge, attitudes, perceptions, and behavioural and social determinants of childhood immunisation, while exploring healthcare workers’ perspectives on factors influencing vaccine uptake. Methods A convergent mixed-methods cross-sectional study was conducted in six districts of Sierra Leone between May and June 2026. Quantitative data were collected from 1,411 caregivers of children aged 12–35 months using structured interviewer-administered questionnaires. Qualitative data were obtained through ten focus group discussions involving 80 caregivers and 60 key informant interviews with healthcare workers. Quantitative data were analysed using descriptive statistics and multivariable logistic regression, while qualitative data underwent thematic analysis guided by the WHO Behavioural and Social Drivers framework. Results Overall, 66.0% of caregivers demonstrated good knowledge, 82.8% had positive attitudes, and 67.4% had positive perceptions towards childhood immunisation. Most respondents had heard of childhood vaccination (96.2%), recognised the importance of completing all vaccine doses (98.2%), and trusted information provided by healthcare workers (96.4%). Positive perceptions of vaccine safety were reported by 87.0% of caregivers. Tertiary education (AOR = 0.27; 95% CI: 0.13–0.55) and formal employment (AOR = 0.38; 95% CI: 0.18–0.80) were associated with lower odds of poor knowledge, while married caregivers had higher odds of poor knowledge (AOR = 3.33; 95% CI: 1.35–8.24). Qualitative findings identified misinformation, transportation difficulties, vaccine stock-outs, inadequate staffing, and competing livelihood priorities as major barriers to vaccination. Conclusion Although caregivers generally demonstrated favourable knowledge and attitudes, behavioural, social, and health system barriers continue to hinder optimal vaccine uptake. Strengthening community engagement, healthcare worker communication, outreach services, and health system capacity will be essential for improving equitable immunisation coverage in Sierra Leone.