A Real-Life Approach for Evaluation of Rapid Ag Testing in Sars-Cov2 Infection

Abstract

Keywords: Respiratory infections;SARS-CoV2;Ag rapid test Received: March 19, 2021, Accepted: April 03, 2021, Published: April 03, 2021 Introduction Biological diagnosis of respiratory infections by SARS-CoV2 uses molecular tools targeting viral genes by RT-PCR analysis or isothermal gene amplification. PCR-positive samples RT-PCR Thermo gave positive results on 86 specimens. * Ct ranged from 10.74 to 40.92 for S target (with 10 lacking of S response due to variations). * Ct ranged from 12.59 to 32.97 for N target. * Ct ranged from 10.41 to 33.68 for Orf1ab target. * For 70 of 86 specimens, all the 3 Ct were <26.00. [...]unexpected negative results by Ag testing (although Ct<26.00 by RT-PCR) were 5 with RAPID TEST 1, 7 with RAPID TEST 2, 2 with AllTest and 2 with Acro Biotech. Variants of SARS-CoV2 Among the 86 RT-PCR positive specimens, there was 10 variants of SARS-COV2: * Two of them (UK and del 69-70 variants) gave a strong and quick positive result by each of the Ag testing device. * Three variant samples gave a negative result by each of the Ag testing device (low burden for two of them: UK and del 69-70 variants;high burden for the other: del 69-70 variant). * Three variant samples gave positive results (even slight or late) for some of the device: RAPID TEST 1 with one ZA variant, RAPID TEST 2 with one UK variant, both RAPID TEST 1 and RAPID TEST 2 with another UK variant. * Two variant samples gave a negative result by one of the 4 devices (AllTest with a del 69-70 variant, low burden) or by two (RAPID TEST 1 and RAPID TEST 2 with a UK variant, high burden).