SARS-CoV-2–Positive Sputum and Feces After Conversion of Pharyngeal Samples in Patients With COVID-19

This study was reported as a letter to the scientific journal Annals of Internal Medicine on 30 March 2020.

The authors report the outcomes of testing for SARS-CoV-2 RNA in sputum and faecal samples from COVID-19 patients after their apparent recovery, which was indicated by throat swabs no longer testing positive.

The key finding was that virus RNA was detected in sputum and faeces up to 39 and 13 days, respectively, after the throat swabs were negative.

This is a significant finding since it may indicate that the patients still harbour the disease and/or that testing these alternative bodily excretions may provide a more sensitive or reliable test than the current reliance on throat swabs.

However, there is a risk that this study may be misreported, or misinterpreted, by some as indicating that these samples (particularly faeces) contain viable, infectious virus.

This study was undertaken by testing for SARS-CoV-2 RNA by real-time quantitative fluorescence polymerase chain reaction (RT-qPCR). This method can detect the presence of parts of the genetic material (RNA) of the virus, but it cannot indicate that infectious virus is present.

It is possible that infectious virus is present in these samples, but alternative culture-based methods would be required to ascertain that it is.

REFERENCE

Chen C, Gao G, Xu Y, Pu L, Wang Q, Wang L, Wang W, Song Y, Chen M, Wang L, Yu F, Yang S, Tang Y, Zhao L, Wang H, Wang Y, Zeng H and Zhang F (2020) SARS-CoV-2–Positive Sputum and Feces After Conversion of Pharyngeal Samples in Patients With COVID-19. Annals of Internal Medicine

https://doi.org/10.7326/M20-0991

Published by Stuart Khan

Professor of Civil & Environmental Engineering, University of New South Wales

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