Dacron swab and PBS are acceptable alternatives to flocked swab and viral transport media for SARS-CoV-2

Kline, Ahnika; Putnam, Nicole E.; Youn, Jung-Ho; East, Amanda; Das, Sanchita; Frank, Karen M.; Zelazny, Adrian M.

Nasopharyngeal flocked swabs placed in viral transport media (VTM) are the preferred collection methodology for respiratory virus testing. Due to the rapid depletion of available reagents and swabs, we have validated an alternative swab placed in phosphate buffered saline (PBS) for use in respiratory virus testing in a SARS-CoV-2 real-time PCR assay and a multiplexed respiratory virus panel. We collected nasopharyngeal (NP) swabs and oropharyngeal (OP) swabs from ten healthy volunteers. Flocked swabs were placed in VTM and alternative swabs in PBS. In this feasibility study, we show that NP collection is better for detection of human material than OP collection, as measured by significantly lower RNase P gene cycle threshold values, and that a dacron polyester swab in PBS shows equivalent detection of SARS-CoV-2 and RSV to a flocked swab in VTM in contrived specimens. Diluted SARS-CoV-2 positive patient specimens are detectable for up to 72 hours at 4 °C.