Seroprevalence of anti-SARS-CoV-2 IgG and IgA antibodies before the launch of COVID-19 vaccination in Kazakhstan.

Abstract

Background: COVID-19 exposure in Central Asia appears underestimated and SARS-CoV-2 seroprevalence data are urgently needed to inform ongoing vaccination efforts and other strategies to mitigate the regional pandemic. Here, we assessed the prevalence of anti-SARS-CoV-2 antibody-mediated immunity in a heterogeneous cohort of public university employees in Karaganda, Kazakhstan. Methods: Asymptomatic subjects (n=100) were randomly recruited prior to their first COVID-19 vaccination. Questionnaires were administered to capture a range of demographic and clinical characteristics. Nasopharyngeal swabs were collected for SARS-CoV-2 RT-qPCR testing. Serological assays were performed to detect spike (S)-reactive IgG and IgA. Results: Anti-S IgG and IgA seropositivity rates among SARS-CoV-2 PCR-negative participants (n=100) were 42% and 53%, respectively, and 61% of subjects tested positive for at least one of the antibodies. Serologically confirmed history of COVID-19 was associated with self-reported history of respiratory illness since March 2020 (p<0.001). Conclusions: SARS-CoV-2 exposure in this cohort is ~15-fold higher compared to the reported all-time national and regional COVID-19 prevalence. Continuous serological surveillance is critical for understanding the COVID-19 transmission dynamics and should be nationally implemented to better inform the public health response in Central Asia.