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

IntroductionHealthcare 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. MethodsA 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 pResultsA 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. ConclusionAlmost 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.