Prolonged presence of SARS‐CoV‐2 viral RNA in faecal samples

Prolonged presence of SARS‐CoV‐2 viral RNA in faecal samples. Spencer EA, Heneghan C.

Published on July 1, 2020

Reference Wu Y, Guo C, Tang L, et al. Prolonged presence of SARS‐CoV‐2 viral RNA in faecal samples. Lancet Gastroenterol Hepatol. 2020. 2020
Study type
Country China
Setting Hospital
Funding Details Grants from National Science and Technology Key Projects for Major Infectious Diseases (2017ZX10302301-002), National Natural Science Foundation of China (31470877), Guangzhou Science and Technology Planning Project (201704020226 and 201604020006), Guangdong Natural Science Foundation (2015A030311009), and National Key Research and Development Program of China (2016YFC1200105).
Transmission mode Orofecal

Bottom Line

In 98 hospitalized COVID-19 cases, patients’ faecal samples remained positive for SARS-CoV-2 for a mean of 11 days (maximum 5 weeks) after respiratory tract samples became negative.

Evidence Summary

Both respiratory and faecal samples were available for 74/98 (76%) study participants. 

Faecal samples from 33 (45%) of 74 participants were negative for SARS CoV-2 RNA, while their respiratory swabs remained positive for a mean of 15 days (SD 6.7) from first symptom onset.

Of the 41 faecal samples that were positive for SARS-CoV-2 RNA, respiratory samples remained positive for a mean of 16.7 days (SD 6.7) and faecal samples for a mean of 27.9 days (10.7) after first symptom onset, i.e., for a mean of 11.2 days (SD 9.2) longer than for respiratory samples.

The presence of gastrointestinal symptoms was not associated with faecal sample viral RNA positivity. Disease severity was not associated with an extended duration of faecal sample viral RNA positivity 

Antiviral treatment was positively associated with the presence of viral RNA in faecal samples.

What did they do?

Between 16th January and 15th March 2020, 98 hospitalised patients with confirmed COVID-19 were enrolled via informed consent into the study.  Real-time RT-PCR was used to detect COVID-19 following the recommended protocol.  Patients with suspected SARS-CoV-2 were confirmed after two sequential positive respiratory tract sample results.

Respiratory and faecal samples were collected every 1 to 2 days (depending on the availability of faecal samples) until two sequential negative results were obtained. Data from medical records were used to obtain information on patient demographics, underlying diseases, clinical indices, and treatments.

Study reliability

This is a small study and therefore reliability is low.  It is not reported why both faecal and respiratory samples were not available for 100% enrolled study participants. Potentially this represents a bias.

Clearly defined setting Demographic characteristics described Follow-up length was sufficient Transmission outcomes assessed Main biases are taken into consideration
Yes No Yes No No

What else should I consider?

Presence of faecal SARS-CoV-2 RNA is likely to lag behind respiratory samples so would not replace testing protocols. Determining whether a virus is viable using nucleic acid detection is difficult; further research is needed to understand transmission potential.

About the authors

Carl Heneghan

Carl is Professor of EBM & Director of CEBM at the University of Oxford. He is also a GP and tweets @carlheneghan. He has an active interest in discovering the truth behind health research findings

Elizabeth Spencer

Dr Elizabeth Spencer; MMedSci, PhD. Epidemiologist, Nuffield Department for Primary Care Health Sciences, University of Oxford.