LAUSR

Background:Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV2), spreads mainly through respiratory drop- lets, aerosols and indirectly through contaminated fomites. Healthcare workers (HCWs) are particularly at risk of infec- tion when caring for such patients. Demonstration of antibodies especially IgG helps to identify the prevalence of SARS - CoV2 infection. Methods:The study was conducted in a 212 bed hospital in Mumbai with a 52 bed isolation facility for COVID 19 pa- tients which included 16 intensive care monitoring beds. The study was conducted between the 3rd and 4th week of July 2020. SARS-CoV2 Total (IgA, IgM & IgG) and IgG antibodies were performed from serum samples using the chemilu- minescence on the VITROS 3600 (Orth clinical diagnostics, USA). The target antigen was the spike protein. Past history of SARS-CoV2 infection by way of PCR was also noted. The cut off optical density (OD) value used for both antibodies was greater than 1. Results:A total of 473 HCWs were tested for total and IgG antibodies. Of these, 294 (62.15%) had been previously tested for SARS-CoV2 PCR either as symptomatic HCWs or as those in high risk contact with positive cases.179 (37.85%) HCWs never went through a PCR. Of these, 28/179(15.64%) HCWs seroconverted indicating asymptomatic past infection. Among the 294 HCWs who were tested by PCR, 88(29.93%) were positive. 22.72% (20/88) PCR positive HCWs did not seroconvert and produce either antibodies. Of the 207 HCWs who were PCR negative, 52(25.12%) seroconverted with either one of the antibodies. Conclusions:The study observed high rates of seroconversion among those who had never tested (15.64%) and those who were PCR negative (25.12%) indicating a high prevalence of infection among HCWs. Another concern observed was that 22.72% of the PCR positive HCWs did not produce antibodies even after 4 weeks.