Seroprevalence of anti-SARS-CoV-2 IgG antibody in hospitalized patients in a tertiary referral center in North India

Ray, A.; Singh, K.; Chattopadhyay, S.; Mehdi, F.; Batra, G.; Gupta, A.; Agarwal, A.; M, B.; Sahni, S.; R, C.; Agarwal, S.; Nagpal, C.; B H, G.; Arora, U.; Sharma, K. K.; Singh Jadon, R.; Datt Upadhyay, A.; Nischal, N.; Vikram, N. K.; Soneja, M.; Pandey, R. M.; Wig, N.

Background: Seroprevalence of IgG antibodies against SARS-CoV-2 is an important tool to estimate the true extent of infection in a population. However, seroprevalence studies have been scarce in South East Asia including India, which, as of now, carries the third largest burden of confirmed cases in the world. The present study aimed to estimate the seroprevalence of the anti-SARS-CoV-2 IgG antibody among hospitalized patients at one of the largest government hospital in India. Method: This cross-sectional study, conducted at a tertiary care hospital in North India, recruited consecutive patients who were negative for SARS-CoV-2 by RT-PCR or CB-NAAT. Anti-SARS-CoV-2 IgG antibody levels targeting recombinant spike receptor-binding domain (RBD) protein of SARS CoV-2 were estimated in serum samples by the ELISA method. Results: A total of 212 hospitalized patients were recruited in the study with mean age (+/-SD) of 41.2 (+/-15.4) years and 55% male population. Positive serology against SARS CoV-2 was detected in 19.8% patients(95% CI 14.7-25.8). Residency in Delhi conferred a higher frequency of seropositivity 26.5% (95% CI 19.3-34.7) as compared to that of other states 8% (95% CI 3.0-16.4) with p-value 0.001. No particular age groups or socio-economic strata showed a higher proportion of seropositivity. Conclusion: Around, one-fifth of hospitalized patients, who were not diagnosed with COVID-19 before, demonstrated seropositivity against SARS-CoV-2. While there was no significant difference in the different age groups and socio-economic classes; residence in Delhi was associated with increased risk (relative risk of 3.62, 95% CI 1.59-8.21) Key Words: SARS-CoV-2 IgG Antibody, Seroprevalence, Hospitalized patient, COVID-19