Rapid volunteer-based SARS-Cov-2 antibody screening among health care workers of a hospital in Mumbai, India

Baveja, Sujata; Karnik, Nitin; Natraj, Gita; Natkar, Milind; Bakshi, Asha; Krishnan, Anand

OBJECTIVES: COVID-19 is highly contagious, and health care workers are at high risk of being infected. We carried out a rapid survey to estimate the proportion of HCWs who are serologically positive for SARS-CoV-2 in the Lokmanya Tilak Municipal General Hospital, Mumbai, India. MATERIAL AND METHODS: After the consent of the hospital authorities, volunteers were asked to report at a special booth set up in the hospital between May 1, 2020, and May 16, 2020. After consent, each worker was administered a questionnaire using a handheld computer which had questions on symptoms in the past 30 days, place of posting (COVID designated area or other), work category (doctor/nurse/others), use of personal protective equipment, smoking, comorbidity, and exposure followed by a test for COVID-19 using the STANDARD Q COVID-19 IgM/ IgG Duo Test of SD Biosensor. We estimated weighted seroprevalence with 95% confidence limits after adjusting for the work category. We calculated the adjusted odds ratio (aOR) using logistic regression with seropositivity as an outcome variable and others as independent variables. RESULTS: The final sample included 501 and 1051 subjects working in the COVID area and non-COVID area, respectively, covering 35% of the total staff of the hospital. Overall, 6.9% (95% CI of 5.7–8.2) of the hospital staff was serologically positive for SARS-Cov-2, similar in the COVID area –5.7 (3.8–8.1) and non-COVID area –7.2 (5.7–9.0). Age more than 50 years (aOR 2.65; 1.45–4.85) and being in others work category 2.84 (1.34–6.02) were identified as significant predictors of being seropositive. Only 10% of the subjects reported COVID-like illness in the past 1 month. CONCLUSION: The overall modest prevalence of infection among the health care workers, especially non-doctors and nurses, and similarity of prevalence in COVID and non-COVID area staff indicate the possibility of non-hospital source of infection.