Fast SARS-CoV-2 detection by RT-qPCR in preheated nasopharyngeal swab samples

Int J Infect Dis. 2020 May 31;97:66-68. doi: 10.1016/j.ijid.2020.05.099. Online ahead of print.

Abstract

Objectives: The gold-standard COVID-19 diagnosis relies on detecting SARS-CoV-2 using RNA purification and one-step retrotranscription and quantitative PCR (RT-qPCR). Based on the urgent need for high-throughput screening, we tested the performance of three alternative, simple and affordable protocols to rapidly detect SARS-CoV-2, bypassing the long and tedious RNA extraction step and reducing the time to viral detection.

Methods: We evaluated three methods based on direct nasopharyngeal swab viral transmission medium (VTM) heating before the RT-qPCR: a) direct without additives; b) in a formamide-EDTA (FAE) buffer, c) in a RNAsnapTM buffer.

Results: Although with a delay in cycle threshold compared to the gold-standard, we found consistent results in nasopharyngeal swab samples that were subject to a direct 70°C incubation for 10 min.

Conclusions: Our findings provide valuable options to overcome any supply chain issue and help to increase the throughput of diagnostic tests, thereby complementing standard diagnosis.

Keywords: COVID-19; RNA extraction; SARS-CoV-2; diagnosis; fast protocols; sample treatment.