COVID-19 vaccine booster uptake among healthcare workers in Bangladesh: predictors, challenges, and lessons from a low-income setting.

BACKGROUND: Healthcare workers (HCWs) remain at an elevated risk of SARS-CoV-2 infection due to occupational exposure and waning vaccine-induced immunity. We conducted a longitudinal study to estimate cumulative uptake, incidence, and factors associated with COVID-19 booster dose uptake among Bangladeshi HCWs. METHODS: Between March 2021 and December 2023, we followed 3099 HCWs recruited from 20 healthcare facilities across four divisions of Bangladesh. At enrollment, information was collected on sociodemographic and clinical characteristics, prior SARS-CoV-2 infection, and COVID-19 vaccination history. Booster uptake status was updated biweekly. Multivariable Cox proportional hazards regression models were used to estimate adjusted hazard ratios (aHRs) for predictors of booster uptake. RESULTS: During follow-up, 1964 (63.4%) HCWs received at least one COVID-19 booster dose. However, uptake of the 2nd booster dose was low (6%). The incidence of booster uptake was 54.5 per 100 person-years (95% CI 50.0-59.5). The hazard of booster uptake was higher among HCWs with prior SARS-CoV-2 infection (aHR = 1.13; 95% CI 1.01-1.26) and among those working in both COVID-19 and general wards (aHR = 1.36; 95% CI 1.22-1.53). In contrast, prior adverse events following the primary series (aHR = 0.36; 95% CI 0.32-0.41) were associated with a lower hazard of booster uptake. CONCLUSIONS: Although more than half of HCWs received a booster, uptake declined with repeated dosing. Variations in the hazard of uptake by occupational exposure, prior infection, and adverse events reflect changing perceptions of risk and experiential factors in addition to access. Strengthening institutional vaccination policies and addressing behavioral barriers may thus support timely booster uptake among HCWs.