Detection of SARS-CoV-2 by Real-Time PCR under challenging pre-analytical conditions reveals independence of swab media and cooling chain

Abstract

With global demand for SARS-CoV-2 testing ever rising, shortages in commercially available viral transport media pose a serious problem for laboratories and health care providers. For reliable diagnosis of SARS-CoV-2 and other respiratory viruses, executed by Real-time PCR, the quality of respiratory specimens, predominantly determined by transport and storage conditions, is crucial. Therefore, our aim was to explore the reliability of minimal transport media, comprising saline and the CDC recommended Viral Transport Media (HBSS VTM), for the diagnosis of SARS-CoV-2 and other respiratory viruses (influenza A, respiratory syncytial virus, adenovirus, rhinovirus and human metapneumovirus) compared to commercial products, such as the Universal Transport Media (UTM). We question the assumptions, that the choice of medium and temperature for storage and transport affect the accuracy of viral detection by RT-PCR. Both alternatives to the commercial transport medium (UTM), namely the CDC viral transport media (HBSS VTM) and saline, allow adequate detection of SARS-CoV-2 and other respiratory viruses, regardless of the storage temperature and time. Our study revealed the high resilience of SARS-CoV-2 and other respiratory viruses, enabling proper detection in clinical specimens even after long-time storage at high temperatures, independent of the transport medium’s composition.

Influence of viral transport media and freeze-thaw cycling on the sensitivity of qRT-PCR detection of SARS-CoV-2 nucleic acids

“…These can be purchased commercially, e.g., universal transport media, UTM ® , or prepared using recipes provided by the US Centre for Disease Control and Prevention (CDC) 17 and the World Health Organization (WHO). 18-20 The importance of VTM selection for accurate qRT-PCR-based molecular diagnostics has been highlighted in a recent study by Kirkland and Frost (2020). It was shown that the composition of commercially available VTM may not always be suitable for the intended purpose, such as nucleic acid detection, which is not always obvious to clinicians and medical scientists.…”