Seroprevalence of SARS-CoV-2 IgG antibodies among asymptomatic whole blood donors at a regional blood transfusion center and association of prevalence with ABO blood group

Background: Serological tests in asymptomatic donors provide may be a source of information on estimate of population-based infection. Serological tests using immunoglobulin G (IgG) can be a useful tool in assessing the disease’s spread if they are carried out serially in a regular manner. We analyzed the pattern in seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG in frequent intervals in an unvaccinated population. Aims and Objectives: This study aimed to study the prevalence of SARS-CoV-2 in asymptomatic blood donors in the period just before vaccine enrollment in Kerala and assess risk factors for SARS-CoV-2 positivity. Materials and Methods: The study was a cross-sectional study in which SARS-CoV-2 IgG positivity was estimated in blood donors attending Government Medical College, Trivandrum from February 1, 2021, to March 31, 2021. The participants responded to a questionnaire also about their demographic characteristics and risk factors. Data were analyzed in SPSS version 17. Results: The overall seroprevalence of COVID-19 anti-IgG antibody in blood donors was 26.4% (191/724). Periodic prevalence was 21.7% in the first half of February, 25.9% in the second half of February, 47.6% in the first half of March, and 25% in 2nd half of March 2021. Non-O group donors carried a higher risk for COVID seropositivity. Conclusion: The seroprevalence of SARS-CoV-2 was higher among the blood donors compared to the general population who were asymptomatic but it reflected the pattern in the general population. No specific risk factor among donor characteristics was identified which can predict seropositivity.