microorganisms Article Multicenter Technical Validation of 30 Rapid Antigen Tests for the Detection of SARS-CoV-2 (VALIDATE) Gilbert Greub 1,2,3, * ,† , Giorgia Caruana 1,† , Michael Schweitzer 4,5 , Mauro Imperiali 6 , Veronika Muigg 4 , Martin Risch 3,6 , Antony Croxatto 1,7 , Onya Opota 1 , Stefanie Heller 4,5 , Diana Albertos Torres 4,5 , Marie-Lise Tritten 7 , Karoline Leuzinger 8,9 , Hans H. Hirsch 8,9,10 , Reto Lienhard 3,7,‡ and Adrian Egli 3,4,8,‡   Citation: Greub, G.; Caruana, G.; Schweitzer, M.; Imperiali, M.; Muigg, V.; Risch, M.; Croxatto, A.; Opota, O.; Heller, S.; Albertos Torres, D.; et al. Multicenter Technical Validation of 30 Rapid Antigen Tests for the Detection of SARS-CoV-2 (VALIDATE). Microorganisms 2021, 9, 2589. https://doi.org/10.3390/ microorganisms9122589 Academic Editors: Célia F. Rodrigues and Natália Cruz-Martins Received: 8 November 2021 Accepted: 4 December 2021 Published: 15 December 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Institute of Microbiology, Lausanne University Hospital, University of Lausanne, 1011 Lausanne, Switzerland; Giorgia.Caruana@chuv.ch (G.C.); Antony.Croxatto@ne.ch (A.C.); Onya.Opota@chuv.ch (O.O.) 2 Infectious Diseases Service, Department of Internal Medicine, Lausanne University Hospital, University of Lausanne, 1011 Lausanne, Switzerland 3 Coordination Commission of Clinical Microbiology, Swiss Society of Microbiology, 1033 Cheseaux, Switzerland; martin.risch@risch.ch (M.R.); Reto.Lienhard@ne.ch (R.L.); Adrian.Egli@usb.ch (A.E.) 4 Clinical Bacteriology and Mycology, University Hospital Basel, 4031 Basel, Switzerland; michael.schweitzer@usb.ch (M.S.); veronika.muigg@usb.ch (V.M.); stefanie.heller@unibas.ch (S.H.); diana.albertostorres@unibas.ch (D.A.T.) 5 Applied Microbiology Research, Department of Biomedicine, University of Basel, 4031 Basel, Switzerland 6 Centro Medicina di Laboratorio Dr Risch, Via Arbostra 2, 6963 Pregassona, Switzerland; mauro.imperiali@risch.ch 7 ADMed Microbiologie Laboratory, 2300 La Chaux-de-Fonds, Switzerland; Marie-Lise.Tritten@ne.ch 8 Clinical Virology, University Hospital Basel, 4031 Basel, Switzerland; Karoline.Leuzinger@usb.ch (K.L.); hans.hirsch@unibas.ch (H.H.H.) 9 Transplantation & Clinical Virology, Department of Biomedicine, University of Basel, 4031 Basel, Switzerland 10 Infectious Diseases and Hospital Epidemiology, University Hospital Basel, 4031 Basel, Switzerland * Correspondence: Gilbert.Greub@chuv.ch † Co-first: contributed equally to this manuscript. ‡ Co-last: contributed equally to this manuscript. Abstract: During COVID19 pandemic, SARS-CoV-2 rapid antigen tests (RATs) were marketed with minimal or no performance data. We aimed at closing this gap by determining technical sensitivities and specificities of 30 RATs prior to market release. We developed a standardized technical validation protocol and assessed 30 RATs across four diagnostic laboratories. RATs were tested in parallel using the Standard Q ® (SD Biosensor/Roche) assay as internal reference. We used left-over universal transport/optimum media from nasopharyngeal swabs of 200 SARS-CoV-2 PCR-negative and 100 PCR-positive tested patients. Transport media was mixed with assay buffer and applied to RATs according to manufacturer instructions. Sensitivities were determined according to viral loads. Specificity of at least 99% and sensitivity of 95%, 90%, and 80% had to be reached for 10 7 , 10 6 , 10 5 virus copies/mL, respectively. Sensitivities ranged from 43.5% to 98.6%, 62.3% to 100%, and 66.7% to 100% at 10 5 , 10 6 , 10 7 copies/mL, respectively. Automated assay readers such as ExDia or LumiraDx showed higher performances. Specificities ranged from 88.8% to 100%. Only 15 of 30 (50%) RATs passed our technical validation. Due to the high failure rate of 50%, mainly caused by lack of sensitivity, we recommend a thorough validation of RATs prior to market release. Keywords: SARS-CoV-2; COVID-19; rapid antigen test; diagnostics; virus testing 1. Introduction The SARS-CoV-2 pandemic has lead to an unprecedented burden of individual and public health [1]. SARS-CoV-2 diagnostic assays became the corner stone of patient care and epidemiological management. Diagnostic laboratories reacted promptly, adapting workflows according to demands [2]. However, in many countries high case numbers Microorganisms 2021, 9, 2589. https://doi.org/10.3390/microorganisms9122589 https://www.mdpi.com/journal/microorganisms