SARS-Coronavirus-2 seroprevalence in asymptomatic healthy blood donors: Indicator of community spread

Background The Corona virus disease 2019 (COVID-19) pandemic caused by SARS -Corona virus-2 (SARS-CoV-2) has been a major concern the world over. Serological surveillance is an important tool to assess the spread of infection in the community. This study attempted to assess the prevalence of antibodies to SARS-CoV-2 among blood donors in Delhi, India during the pre-vaccination period. Methods Seroprevalence of SARS-CoV2-2 IgG antibodies were determined in blood donors reporting to the Department of Transfusion medicine at a tertiary care hepatobiliary center, in India from September to October 2020. The SARS-CoV-2 IgG antibodies against spike subunit 1 protein were measured using the enhanced chemiluminescence method. Results A total of 1066 blood donors were screened. The overall seropositivity for SARS-CoV-2 IgG antibodies was 27.57 % (294/1066). The highest seropositivity was seen in the age group 26−35 years, 46.6 % (137/492), followed by 18−25 years, 28.2 % (83/260), 36−45 years, 19.4 % (57/244), and more than 45 years, 5.8 % (17/70). The seropositivity in the donors who had donated blood previously was 26.1 % (189/723). There was no statistically significant difference amongst seroprevalence in the blood groups, AB blood group (32.6 %, 95 % CI 23.02−43.3), group B (27.2 %, 95 % CI 22.8−32.09 %), group A (27.1 %, 95 % CI 21.8−32.9 %), and group O (27.02 %, 95 % CI 22.3−32.1 %) (p 0.539). Conclusions There was significantly higher seropositivity for SARS-CoV-2 antibodies in the voluntary healthy blood donors indicating community spread and large number of asymptomatic cases in Delhi. Higher seroprevalence in younger adults indicated increased exposure to the virus and lack of COVID appropriate behaviour.