S1 Data -

Introduction
The vaccination against coronavirus disease 2019 (COVID-19) has been identified as a promising strategy to reduce the severity of the pandemic. Despite the safe and effective COVID-19 vaccines, bringing socioeconomically disadvantaged people under vaccination coverage has been challenging for developing countries like Bangladesh. Therefore, this study explored the determinants of vaccine acceptance among urban slum residents of Bangladesh using the Health Belief Model (HBM) and Theory of Planned Behavior (TPB).
Methods
A face-to-face survey of 400 urban slum dwellers in two large cities in Bangladesh was conducted between July 5 to August 5, 2021. The questionnaire included vaccine acceptance, socio-demographics, health-related characteristics, trust in health authorities, reasons for vaccine hesitancy, and dimensions of HBM and TPB frameworks. Hierarchical logistic regression was performed to evaluate the association between these characteristics and vaccination acceptance.
Results
Around 82% (n = 327) of respondents were willing to accept the COVID-19 vaccine. In a fully adjusted model, respondents with secondary level education had higher intention (OR = 46.93, 95%CI = 1.21–1807.90, p < 0. 05) to accept COVID-19 vaccine. Respondents with bad (OR = 0.11, 95%CI = 0.01–0.35, p<0.05) or very bad (OR = 0.01, 95%CI = 0.01–0.35, p<0.05) health conditions were less interested in the COVID-19 vaccination. In regard to HBM dimensions, greater perceived susceptibility (OR = 1.75, 95% CI = 1.12–2.75, p < 0.05), and perceived benefits (OR = 3.28, 95% CI = 1.17–6.00, p < 0.001) were associated with a greater willingness to get vaccinated. In regard to TPB, higher self-efficacy in preventing illness without the vaccine increased the desire to get vaccinated (OR = 1.55, 95% CI = 1.02–2.37, p < 0.05). Fear of unknown side effects, religious beliefs, contraindications to vaccination, and insufficient information on the vaccine were the main reasons for vaccine hesitancy.
Conclusions
These findings offer valuable insights for policymakers in Bangladesh to design targeted interventions that address vaccine hesitancy and increase vaccination acceptability among socially disadvantaged individuals in urban areas. Strategies should focus on providing accurate and accessible information about the vaccine, communicating its positive impact effectively, engaging with religious leaders to address misconceptions, and tailoring vaccination campaigns to meet the unique needs of different demographic groups.