Rapid COVID-19 antigenic tests: Usefulness of a modified method for diagnosis.

The current reliable recommended test for COVID-19 diagnosis is RT-qPCR. Rapid antigen test devices could be useful as they are less expensive, faster without the need of specialized laboratories to perform the test. We report the performances of 2 rapid immunochromatographic antigen testing devices compared to RT-qPCR for SARS-CoV-2 detection in clinical samples. We carried out a lateral-flow tests study on 401 nasopharyngeal swab samples from non-duplicated suspected COVID-19 subjects. An equal volume of UTM-containing samples (dilution ratio = 1:15) were added to manufacturer's extraction buffer solution (dilution ratio = 1:2) and analyzed on BioSpeedia COVID19Speed-Antigen Test and on Abbott Panbio COVID-19 Ag Rapid Test, devices. Qualitative results were compared to those obtained by the RT-qPCR (Allplex™ SARS-CoV-2 Assay Seegene). Based on our data, overall sensitivity for BioSpeedia and Panbio devices were estimated at 65.5 and 75.0 %, respectively. The sensitivity was greater for cycle threshold values less than 25 achieving 90.4 and 96.8 for BioSpeedia and Panbio devices, respectively. A perfect specificity of 100.0% was observed for both devices. BioSpeedia and Panbio, as rapid antigen tests with excellent sensitivity to detect high viral loads, appeared to be reliable alternatives to RT-qPCR especially valuable when molecular testing capacity may be saturated by overflow of samples. Given the high specificity of devices, a positive result would not require confirmation by a molecular test and would therefore allow a faster management of COVID-19-positive patients. This article is protected by copyright. All rights reserved