1. Severe Acute Respiratory Syndrome Coronavirus 2 Seroassay Performance and Optimization in a Population With High Background Reactivity in Mali.
- Author
-
Woodford J, Sagara I, Dicko A, Zeguime A, Doucoure M, Kwan J, Zaidi I, Doritchamou J, Snow-Smith M, Alani N, Renn J, Kosik I, Holly J, Yewdell J, Esposito D, Sadtler K, and Duffy P
- Subjects
- Adult, COVID-19 blood, Enzyme-Linked Immunosorbent Assay, Humans, Immunoglobulin G, Mali epidemiology, Sensitivity and Specificity, Spike Glycoprotein, Coronavirus chemistry, Antibodies, Viral blood, COVID-19 epidemiology, SARS-CoV-2 immunology, Spike Glycoprotein, Coronavirus immunology
- Abstract
Background: False positivity may hinder the utility of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serological tests in sub-Saharan Africa., Methods: From 312 Malian samples collected before 2020, we measured antibodies to the commonly tested SARS-CoV-2 antigens and 4 other betacoronaviruses by enzyme-linked immunosorbent assay (ELISA). In a subset of samples, we assessed antibodies to a panel of Plasmodium falciparum antigens by suspension bead array and functional antiviral activity by SARS-CoV-2 pseudovirus neutralization assay. We then evaluated the performance of an ELISA using SARS-CoV-2 spike protein and receptor-binding domain developed in the United States using Malian positive and negative control samples. To optimize test performance, we compared single- and 2-antigen approaches using existing assay cutoffs and population-specific cutoffs., Results: Background reactivity to SARS-CoV-2 antigens was common in prepandemic Malian samples. The SARS-CoV-2 reactivity varied between communities, increased with age, and correlated negligibly/weakly with other betacoronavirus and P falciparum antibodies. No prepandemic samples demonstrated functional activity. Regardless of the cutoffs applied, test specificity improved using a 2-antigen approach. Test performance was optimal using a 2-antigen assay with population-specific cutoffs (sensitivity, 73.9% [95% confidence interval {CI}, 51.6-89.8]; specificity, 99.4% [95% CI, 97.7-99.9])., Conclusions: We have addressed the problem of SARS-CoV-2 seroassay performance in Africa by using a 2-antigen assay with cutoffs defined by performance in the target population., (Published by Oxford University Press for the Infectious Diseases Society of America 2021.)
- Published
- 2021
- Full Text
- View/download PDF