Comparison of Throat Washings, Nasopharyngeal Swabs and Oropharyngeal Swabs for Detection of SARS-CoV-2

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) RNA is detected by reverse-transcription quantitative real-time PCR (RT-qPCR) from respiratory specimens. This study compares throat washings (TW), nasopharyngeal swabs (NS) and oropharyngeal swabs (OS). A total of 102 samples from 34 adult patients with confirmed SARS-CoV-2 infection were analysed by RT-qPCR with absolute quantification. The median concentrations and diagnostic sensitivities were 5.8x10(4) copies/mL, 85% (NS), 1.4x10(4), 79% (OS) and 4.3x10(3), 85% (TW). Concentration differences were significant between NS and TW (P = 0.019). Saliva (SA) was available from 21 patients (median 3.4x10(3)). OS and TW can be considered for SARS-CoV-2 diagnostics, although with slightly lower concentrations.

Automated summary

This study compared the diagnostic performance of throat washings (TW), nasopharyngeal swabs (NS) and oropharyngeal swabs (OS) in detecting SARS-CoV-2 RNA. Nasopharyngeal swabs showed higher concentrations and diagnostic sensitivities, with significant concentration differences between NS and TW. Oropharyngeal swabs (OS) and throat washings (TW) can still be considered for SARS-CoV-2 diagnostics, albeit with slightly lower concentrations.