Vaccination status and re-infection among COVID patients admitted in COVID High Dependency Unit (HDU) of a tertiary hospital in Eastern Nepal: A cross-sectional study

Introduction The relationship between COVID-19 vaccination and Coronavirus disease severity and outcomes remain topics of significant interest. This cross-sectional study done among COVID-19 patients admitted to the High-dependency unit of a tertiary hospital in Eastern Nepal aimed to assess the association between vaccination status, prior infection, and disease outcomes, and the modification of these associations by the presence or absence of comorbidities. Methodology Demographic and clinical data were collected from 102 COVID-19 patients admitted to the High-Dependency Unit of Mechi Zonal Hospital, including information on vaccination status, comorbidities, disease severity, and outcomes. Statistical analysis, including chi-square tests and Fisher’s exact tests, was performed to examine the associations. Results Among the study participants, 49% had received at least one dose of COVID-19 vaccine. Vaccinated individuals had a significantly lower rate of severe disease compared to non-vaccinated individuals (χ²=10.05, p=0.002). Recovery and mortality rates did not differ significantly between the two groups (χ²=1.008, p=0.315). However, when stratified by comorbidities, vaccinated individuals with comorbidities had higher recovery rates compared to non-vaccinated individuals (85.29% vaccinated vs. 25.00% non-vaccinated, Fisher’s exact test p=0.024). Vaccinated individuals, both with and without comorbidities, had lower rates of severe disease compared to non-vaccinated individuals. However, the association was found to be significant only in individuals with comorbidities (12.50% vaccinated without comorbidities vs. 47.92% non-vaccinated, p=0.017; 23.53% vaccinated with comorbidities vs. 75.00% non-vaccinated, p=0.065). Conclusion Our findings suggest that COVID-19 vaccination is associated with a reduced risk of severe disease among individuals with or without comorbidities and decreased risk of mortality among those with comorbidities. However, larger studies are needed to validate these findings and further explore the impact of vaccination on disease outcomes. These findings support the ongoing efforts to promote COVID-19 vaccination as a crucial public health intervention.