Evaluation of Saline, Phosphate-Buffered Saline, and Minimum Essential Medium as Potential Alternatives to Viral Transport Media for SARS-CoV-2 Testing
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), has caused a global pandemic since being discovered in late 2019. In response, clinical microbiology and public health laboratories have worked to develop, validate, and implement molecular assays to detect SARS-CoV-2 from respiratory samples. The preferred and most commonly collected specimen is a nasopharyngeal (NP) swab placed in viral transport media (VTM). As testing demand has increased, specimen collection and transportation supplies, including VTM, are decreasing nationwide. Due to these shortages of collection supplies and transport media, we assessed the feasibility of placing NP swabs in sterile 0.9% saline (Baxter, Deerfield, IL), sterile phosphate-buffered saline without calcium and magnesium (PBS), or minimum essential medium (MEM) (Corning, Corning, NY) prior to testing
for SARS-CoV-2 by a commercially available (emergency use authorized [EUA]) FDA platform (cobas SARS-CoV-2; Roche Diagnostics, Indianapolis, IN) and a SARS-CoV-2 laboratory-developed test (LDT) that has been validated and submitted to the Food and Drug Administration for EUA approval. The Roche cobas SARS-CoV-2 test is performed on the cobas 6800 platform (Roche) per the manufacturer’s protocol. The SARS-CoV-2 LDT is performed as described in the supplemental material, targeting the nucleocapsid (NUC) and open reading frame (ORF) regions of the virus.