1. Severe Acute Respiratory Syndrome Coronavirus 2 Seroassay Performance and Optimization in a Population With High Background Reactivity in Mali
- Author
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M'Bouye Doucoure, Jennifer Kwan, John Woodford, Irfan Zaidi, Justin Doritchamou, Jaroslav Holly, Kaitlyn Sadtler, Patrick E. Duffy, Alassane Dicko, Nada Alani, Amatigue Zeguime, Dominic Esposito, Jonathan P. Renn, Maryonne Snow-Smith, Ivan Kosik, Issaka Sagara, and Jonathan W. Yewdell
- Subjects
education.field_of_study ,Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) ,Population ,Biology ,medicine.disease_cause ,biology.organism_classification ,Cross-reactivity ,Virology ,Neutralization ,Serology ,Infectious Diseases ,Antigen ,parasitic diseases ,medicine ,biology.protein ,Immunology and Allergy ,Antibody ,education ,Betacoronavirus - 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
- 2021