Prevalence of anti-SARS-CoV-2 immunity in Kazakhstan before the launch of COVID-19 vaccination

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.

High SARS-CoV-2 seroprevalence in Karaganda, Kazakhstan before the launch of COVID-19 vaccination

“…To date, the extent of community exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Kazakhstan is incompletely understood. Thus, as of 7 August 2021 (when analysis presented in this work was completed [ 5 ]), the officially reported number of all-time COVID-19 cases in Kazakhstan was 689,402 (626,402 of which were PCR-confirmed, while the rest were diagnosed based on clinical disease manifestations). These figures represented a cumulative prevalence of ~3.7% [ 6 ]- a prevalence that appears low given the substantial excess of infections and mortality estimated for Kazakhstan consistent with COVID-19 [ 2 , 3 ].…”

“…We thank all the study participants and the COVID-19 vaccination clinic staff. We acknowledge that an earlier draft of this manuscript appeared online as a medRxiv preprint [ 5 ].…”