Covid-19 second dose vaccine uptake and associated factors: A community-based cross-sectional study among adults in Masindi district in Uganda

While Uganda has achieved relatively high COVID-19 first dose vaccination rates, completion of the second dose remains low, particularly in Masindi district where only 44.0% of adults who were vaccinated with the first dose proceeded to receive the second dose. This shortfall threatens to undermine the achievement of herd immunity and the effectiveness of the nation's COVID-19 vaccination campaign. This study aimed to determine the rate of second dose vaccine uptake and assess factors associated with second dose uptake among adults in Masindi district. We conducted a community-based cross-sectional study using multi-stage random sampling approach to select 637 study respondents. Data were collected using a pre-tested interviewer-administered structured questionnaire and analyzed using SPSS v26. Modified Poisson regression was used to identify independent predictors of second dose uptake. Results were reported using adjusted prevalence ratios (APRs) and 95% confidence intervals (CIs), with statistical significance set at p<0.05. Among adults who had received at least one dose of a COVID-19 vaccine, 44.0% had completed the two-dose vaccination schedule. Independent factors significantly associated with higher second dose uptake included high economic status (APR = 2.2, 95% CI: 1.16-3.07), urban residence (APR = 1.3, 95% CI: 1.13-1.62), high perceived risk of COVID-19 (APR = 2.0, 95% CI: 1.59-2.55), chronic illness (APR 1.9; 95% CI: 1.60-2.33), living less than 1 km from a vaccination site (APR = 2.0, 95% CI: 1.49-3.01), Shorter waiting times ; under 30 minutes (APR = 1.7, 95% CI: 1.41-2.08), community/religious leaders’ support (APR = 1.7, 95% CI: 1.41-2.16), Community outreach programs (APR = 2.5, 95% CI: 1.99-3.36), and Exposure to vaccination information through radio or TV (APR = 1.5, 95% CI: 1.25–1.88). Vaccine shortages (APR = 0.4, 95% CI: 0.31-0.55), and experiencing of adverse side effects after the first dose (APR = 0.8, 95% CI: 0.71-0.97) were associated with reduced prevalence of receiving a second dose. The findings suggest that COVID-19 vaccine second dose uptake in Masindi district remains low and is associated with interconnected socioeconomic, individual, health system, and community-level factors. Interventions should consider improving access, risk communication, and engagement of community structures are needed to boost vaccine completion rates.