The following is a summary of “SARS-CoV-2 Serosurveys: How Antigen, Isotype, and Threshold Choices Affect the Outcome,” published in the 1 February 2023 issue of Infectious Diseases by Binder, et al.

Understanding the incidence of infection within certain areas required evaluating the efficacy of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serological assays and defining the utility of chosen antigens, isotypes, and thresholds.

The cross-sectional study, conducted in 2020, used an enzyme-linked immunosorbent assay to detect anti-SARS-CoV-2 receptor-binding domain, trimeric spike protein, and nucleocapsid protein immunoglobulin (Ig)G and IgA antibodies in PCR-confirmed coronavirus disease 2019 patients (n = 86), banked pre-pandemic and negative samples (n = 96), healthcare workers and their families (n = 552), and university employees (n = 327). The mean +3 standard deviations of the negative controls, 100% specificity for each antigen-isotype combination, and the maximum Youden index were the assessed threshold techniques.

They discovered a wide range of seroprevalence estimations, from 0.0% to 85.4%, depending on the chosen antigens and isotypes, and the threshold approach used. We then increased specificity and reported a seroprevalence based on several antigens that ranged from 9.3% to 25.9%.

To interpret qualitative serosurvey results reliably and consistently across studies, it was crucial to assess the sensitivity and specificity of serosurvey methods for antigen-, isotype-, and threshold-specific data.