Cancer Diagnosis Program | Biorepositories and Biospecimen Research Branch

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Evaluation of saline, phosphate buffered saline and minimum essential medium as potential alternatives to viral transport media for SARS-CoV-2 testing.

Author(s): Rodino KG, Espy MJ, Buckwalter SP, Walchak RC, Germer JJ, Fernholz E, Boerger A, Schuetz AN, Yao JD, Binnicker MJ

Publication: J Clin Microbiol, 2020, Vol. , Page

PubMed ID: 32229604 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   The purpose of this study was to investigate the stability of SARS-CoV-2 in different media over seven days of frozen or refrigerated storage. A total of 48 nasopharyngeal swabs from patients who tested negative for SARS-CoV-2 were placed into tubes containing 3 mL of M4-RT viral transport media (VTM), minimum essential media (MEM), saline, or PBS. Forty specimens (10 in each media type) were subsequently spiked with SARS-CoV-2 positive material at a concentration of 10,000 copies/mL, while the remaining eight specimens were kept as negative controls. Tubes were stored at 2 to 8°C or -15 to -25°C for 0, 1, 3, or 7 days before testing. SARS-CoV-2 was detected using two different real-time PCR-based assays: the Roche Cobas amplification of the open reading frame and envelope RNA and LDT SARS-CoV-2 amplification of the open reading frame and nucleocapsid RNA. All results were compared to those of the specimen in VTM.

   Summary of Findings:

   CT values were within 2 cycles for all the specimens regardless of storage media and duration, indicating no change in sensitivity or stability over the 7-day period at either temperature. One specimen (stored in PBS) had lower CT values on days 1, 3, and 7 which the authors state may be due to variation in sample preparation. The CT values differed slightly between the two methods but both SARS-CoV-2 amplicons were detected in all specimens using both assays.

   Biospecimens

   • Cell - Nasopharynx

   Preservative Types

   • Frozen
   • None (Fresh)

   Diagnoses:

   • Pneumonia/Respiratory Infection

   Platform:

   Analyte	Technology Platform
   RNA	Real-time qRT-PCR

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Storage	Short-term storage solution	M4-RT VTM PBS Saline MEM
   Storage	Storage duration	0 days 1 day 3 days 7 days
   Real-time qRT-PCR Specific	Technology platform	Roche cobas LDT SARS-CoV-2 amplification
   Real-time qRT-PCR Specific	Targeted nucleic acid	SARS-CoV-2 open reading frame SARS-CoV-2 nucleocapsid, Envelope SARS-CoV-2 envelope
   Storage	Storage temperature	2-8°C -15 to -25°C

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