Serology assays used in SARS-CoV-2 seroprevalence surveys worldwide: a systematic review and meta-analysis of assay features, testing algorithms, and performance

Abstract

Background: Many SARS-CoV-2 serological assays were rapidly developed during the COVID-19 pandemic. However, differences in detection mechanism limit the comparability of assay outputs. Methods: As part of the SeroTracker global living systematic review of SARS-CoV-2 seroprevalence studies, we collated serological assays used in serosurveys between January 1, 2020 and November 19, 2021. We mapped performance metrics to the manufacturer, third-party head-to-head, and independent group evaluations, comparing the assay performance data using a mixed-effect beta regression model. Results: Among 1807 serosurveys, 192 distinctive commercial assays and 380 self-developed assays were identified. According to manufacturers, 28.6% of all commercial assays met WHO criteria for emergency use (sensitivity [Sn.] >= 90.0%, specificity [Sp.] >= 97.0%). Third-party and independent evaluations indicated that manufacturers overstated the Sn. of their assays by 5.4% and 2.8%, and Sp. by 6.3% and 1.2%. We found in simulations that inaccurate Sn. and Sp. can substantially bias seroprevalence estimates corrected for assay performance. Conclusions: The Sn. and Sp. of the serological assay are not fixed properties, but varying features depending on testing population. To achieve precise population estimates and to ensure comparability, serosurveys should select assays with strong, independently validated performance and adjust seroprevalence estimates based on assured performance data.