Assessment of potential risk factors for COVID-19 among health care workers in a health care setting in Delhi, India -a cohort study

INTRODUCTION: Healthcare workers (HCW) are most vulnerable to contracting COVID-19 infection. Understanding the extent of human-to-human transmission of the COVID-19 infection among HCWs is critical in managing this infection and for policy making. We did this study to estimate new infection by seroconversion among HCWs in recent contact with COVID-19 and predict the risk factors for infection. METHODS: A cohort study was conducted at a tertiary care COVID-19 hospital in New Delhi during the first and second waves of the COVID-19 pandemic. All HCWs working in the hospital during the study period who came in recent contact with the patients were our study population. The data was collected by a detailed face-to-face interview, serological assessment for anti- COVID-19 antibodies at baseline and end line, and daily symptoms. Potential risk factors for seroprevalence and seroconversion were analyzed by logistic regression keeping the significance at p<0.05. RESULTS: A total of 192 HCWs were recruited in this study, out of which 119 (62.0%) were seropositive. Almost all were wearing Personal protective equipment (PPE) and following Infection prevention and control (IPC) measures during their recent contact with a COVID-19 patient. Seroconversion was observed among 36.7% of HCWs, while 64.0% had a serial rise in the titer of antibodies during the follow-up period. Seropositivity was negatively associated with being a doctor (odds ratio [OR] 0.35, 95% Confidence Interval [CI] 0.18–0.71), having COVID-19 symptoms (OR 0.21, 95% CI 0.05–0.82), having comorbidities (OR 0.14, 95% CI 0.03–0.67), and received IPC training (OR 0.25, 95% CI 0.07–0.86), while positively associated with partial (OR 3.30, 95% CI 1.26–8.69), as well as complete vaccination for COVID-19 (OR 2.43, 95% CI 1.12–5.27). Seroconversion was positively associated with doctor as a profession (OR 13.04, 95% CI 3.39–50.25) and with partially (OR 4.35, 95% CI 1.07–17.65), as well as fully vaccinated for COVID-19 (OR 6.08, 95% CI 1.73–21.4). No significant association was observed between adherence to any IPC measures and PPE adopted by the HCW during the recent contact with COVID-19 patients and seroconversion. CONCLUSION: Almost all the HCW practiced IPC measures in these settings. High seropositivity and seroconversion are most likely due to concurrent vaccination against COVID-19 rather than recent exposure to COVID-19 patients. Further studies using anti-N antibodies serology may help us find the reason for the seropositivity and seroconversion among HCWs.