Association of Clinicodemographic Factors and Vaccination Status with COVID-19 Positivity in a Tertiary Care Hospital in Southern India: A Cross-sectional Study

Introduction: The Coronavirus Disease-2019 (COVID-19) pandemic has wreaked havoc all over the world during the past three years claiming millions of lives. Though the World Health Organisation (WHO) on May 4th 2023 declared that it is no longer a Public Health Emergency of International Concern, it continues to be a global threat with the possibility of emergence of new variants. Aim: To assess the clinicodemographic factors associated with COVID-19 infection and to determine the correlation between vaccination status and COVID-19 positivity. Materials and Methods: An electronic record-based crosssectional study was conducted from April 2021 to September 2021 in the Department of Microbiology, Shridevi Institute of Medical Sciences and Research Hospital, Tumkur, Karnataka, India. Data pertaining to demographics, symptoms, presence of co-morbidities and vaccination status were collected from individuals whose samples were received for COVID-19 testing either by Real Time-Polymerase Chain Reaction (RT-PCR) or Rapid Antigen Test (RAT). A bivariate analysis was performed using logistic regression to identify factors that were associated with COVID-19 positivity. Multivariate logistic regression was used to assess the relationship between variables after adjusting for potential confounders. Spearman correlation coefficient was calculated to assess the relationship between vaccination status and COVID-19 positivity. Results: A total of 14,846 patients were included in the study. Having at least one co-morbid condition increased the odds of COVID-19 positivity by 28% (AOR: 1.28; 95% CI: 1.01-1.63, p-value=0.039) whereas female gender had 22% (OR: 0.78, 95% CI; 0.72-0.85, p-value=<0.001) lower risk of association with COVID-19 positivity. A weak negative correlation was demonstrated between COVID-19 vaccination status and COVID-19 positivity (Spearman’s Rho ρs=-0.1209, p=<0.01) showing decreased rate of COVID-19 positivity with increase in rate of vaccination. Bivariate analysis of COVID-19 positivity among vaccinated and unvaccinated individuals revealed a significant reduction in odds of testing COVID-19 positive after vaccination (p-value <0.001). Multivariate analysis after adjusting for the effects of age, gender and time of pandemic, showed that receiving a single dose of COVID-19 vaccine reduced the odds of having a COVID-19 positive status by 32% (AOR: 0.68, 95% CI: 0.56-0.82; p-value <0.001) and receiving two doses lowered the odds by 59% (AOR: 0.41, 95% CI: 0.31-0.53; p-value <0.001). Conclusion: This study shows that vaccination against COVID19 was associated with decreased rate of COVID-19 positivity and demonstrated that two-doses of vaccination was more effective than a single dose.