Evaluation of the impact of pre-analytical conditions on sample stability for the detection of SARS-CoV-2 RNA
Author(s)
Type
Journal Article
Abstract
Demand for accurate SARS-CoV-2 diagnostics is high. Most samples in the UK are collected in the community and rely on the postal service for delivery to the laboratories. The current recommendation remains that swabs should be collected in Viral Transport Media (VTM) and transported with a cold chain to the laboratory for RNA extraction and RT-qPCR. This is not always possible. We aimed to test the stability of SARS-CoV-2 RNA subjected to different pre-analytical conditions. Swabs were dipped into PBS containing cultured SARS-CoV-2 and placed in either a dry tube or a tube containing either normal saline or VTM. The tubes were then stored at different temperatures (20–50 °C) for variable periods (8 h to 5 days). Samples were tested by RT-qPCR targeting SARS-CoV-2 E gene. VTM outperformed swabs in saline and dry swabs in all conditions. Samples in VTM were stable, independent of a cold chain, for 5 days, with a maximum increase in cycle threshold (Ct) of 1.34 when held at 40 °C. Using normal saline as the transport media resulted in a loss of sensitivity (increased Ct) over time and with increasing temperature (up to 7.8 cycles compared to VTM). SARS-CoV-2 was not detected in 3/9 samples in normal saline when tested after 120 h incubation. Transportation of samples in VTM provides a high level of confidence in the results despite the potential for considerable, uncontrolled variation in temperature and longer transportation periods. False negative results may be seen after 96 h in saline and viral loads will appear lower.
Date Issued
2022-11-01
Date Acceptance
2022-08-11
Citation
Journal of Virological Methods, 2022, 309, pp.1-5
ISSN
0166-0934
Publisher
Elsevier
Start Page
1
End Page
5
Journal / Book Title
Journal of Virological Methods
Volume
309
Copyright Statement
© 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
License URL
Sponsor
National Institute for Health Research
UK Research and Innovation
Identifier
https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000860502200001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Grant Number
RP-2016-07-012
9815274 MC_PC_19025
Subjects
Science & Technology
Life Sciences & Biomedicine
Biochemical Research Methods
Biotechnology & Applied Microbiology
Virology
Biochemistry & Molecular Biology
SARS-CoV-2
Diagnosis
RT-qPCR
RNA
Sample stability
Publication Status
Published
Article Number
ARTN 114607
Date Publish Online
2022-08-13