Post-Vaccination COVID-19 Infection and Its Correlates among Residents of Chandra, Gazipur, Bangladesh: A Cross-Sectional Study

Background: COVID 19 vaccines are highly effective at preventing severe disease and death but post vaccination (breakthrough) infections are still seen, especially with immune-evasive variants. There is some evidence at the community level from Bangladesh. The aim of this study was to estimate prevalence, clinical profile and correlates of post-vaccination COVID 19 infection in Chandra, Kaliakair, Gazipur, Bangladesh. Methods: This was a community based cross-sectional study that included adults & 8805;18 years of age with at least one dose of a COVID 19 vaccine from March 2021 to December 2022. The respondents were 300 people who were selected by multistage sampling technique and interviewed with a pretested semi-structured questionnaire. Demographic, vaccination history, post vaccination infection, clinical features, preventive behaviours, knowledge and comorbidities data were gathered. The chi square test was used to test the bivariate associations and multivariable binary logistic regression was used to identify independent correlates. A p value of < 0.05 was used to determine statistical significance. Ethical Approval took from the IRB board of SCMST. Results: Among 300 participants (mean age 48.0 17.6 years; 52.0% male), 124 (41.3%) reported COVID 19 infection after vaccination. Of these, 24 (19.4%) were asymptomatic, 67 (54.0%) had mild disease, 24 (19.4%) had moderate disease, and 9 (7.3%) had severe disease; only 12 (9.7%) required hospitalisation. In multivariable analysis, rural residence (adjusted odds ratio [aOR] 4.87; 95% CI 2.42 9.79), poor mask use (aOR 2.28; 95% CI 1.31 3.97), poor physical distancing (aOR 2.74; 95% CI 1.55 4.86), poor hand hygiene (aOR 3.61; 95% CI 2.05 6.38), and diabetes (aOR 4.46; 95% CI 1.97 10.14) were independently associated with higher odds of infection, whereas receipt of a booster dose was protective (aOR 0.23; 95% CI 0.13 0.42). Conclusion: P st-vaccination infection was common but largely mild and hospitalisation was rare. The booster vaccination was protective and factors such as rural residence, poor preventive practices and diabetes were risk factors for infection. These results do reinforce the importance of booster doses coupled with ongoing preventive behaviour and targeted interventions for clinically vulnerable populations.