J Med Virol

. 2021 Feb 8.
doi: 10.1002/jmv.26855. Online ahead of print.
Diagnosis value of SARS-CoV-2 antigen/antibody combined testing using rapid diagnostic tests at hospital admission

Nicolas Veyrenche 1 , Karine Bollor? 1 , Amandine Pisoni 1 , Anne-Sophie Bedin 1 , Anne-Marie Mondain 2 , Jacques Ducos 2 , Michel Segondy 1 , Brigitte Montes 2 , Patrick Pastor 2 , David Morquin 3 4 , Alain Makinson 3 4 , Vincent Le Moing 3 4 , Philippe Van de Perre 1 , Vincent Foulongne 1 , Edouard Tuaillon 1



Objectives: The implementation of rapid diagnostic tests (RDTs) may enhance the efficiency of SARS-CoV-2 testing, as RDTs are widely accessible and easy to use. The aim of this study was to evaluate the performance of a diagnosis strategy based on a combination of antigen and IgM/IgG serological RDTs.
Methods: Plasma and nasopharyngeal samples were collected between 14 March and 11 April 2020 at hospital admission from 45 patients with RT-PCR confirmed COVID-19 and 20 negative controls. SARS-CoV-2 antigen (Ag) was assessed in nasopharyngeal swabs using the Coris Respi-Strip. For IgM/IgG detection, SureScreen Diagnostics and Szybio Biotech RDTs were used in addition to laboratory assays (Abbott Alinity i SARS-CoV-2 IgG and Theradiag COVID-19 IgM ELISA).
Results: Using the Ag RDT, 13 out of 45 (29.0%) specimens tested positive, the sensitivity was 87.0% for Cycle Threshold (CT) values ≤ 25 and 0% for CT values > 25. IgG detection was associated with high CT values and the amount of time after the onset of symptoms. The profile of isolated IgM on RDTs was more frequently observed during the first and second week after the onset of symptoms. The combination of Ag and IgM/IgG RDTs enabled the detection of up to 84.0% of COVID-19 confirmed cases at hospital admission.
Conclusion: Antigen and antibody-based RDTs showed suboptimal performances when used alone. However when used in combination, they are able to identify most COVID-19 patients admitted in an emergency department. This article is protected by copyright. All rights reserved.

Keywords: Coronavirus disease-19 (COVID-19); Diagnosis; SARS-CoV-2 antibody; SARS-CoV-2 antigen; rapid diagnostic tests.