Faecal-to-oral SARS-CoV-2 transmission probable

A substantial proportion of COVID-19 patients shed SARS-CoV-2 viral RNA in faeces, with the virus persisting long after respiratory testing has become negative, according to the results of a meta-analysis. This suggests that the disease can be spread via the faecal–oral route.

Researchers conducted a systematic review of studies and retrieved 95 studies to critically assess performance and accuracy of testing stool samples or anal swabs in relation to the potential of orofaecal transmission of SARS‐CoV‐2.

The majority of the included studies were performed in China (n=74), while other studies were conducted in Korea (n=6), Singapore (n=2), US (n=5), Italy (n=4), France (n=1), Germany (n=1), Thailand (n=1), and Austria (n=1). Seventeen studies tested SARS‐CoV‐2 presence in anal swabs and 81 in stool samples; both specimens were tested in three studies.

Real‐time reverse transcription polymerase chain reaction (RT‐PCR) was used to detect SARS‐CoV‐2 in nearly all studies, whereas one study performed inoculation of stool suspension into Vero cells followed by virus detection through electron microscopy.

Out of the 2,149 patients overall, 934 (43 percent) tested positive for SARS‐CoV‐2 in stool samples or anal swabs. Some of the tests that returned positive were conducted as late as 70 days after symptom onset.

A meta‐analysis including studies with ≥10 patients revealed a pooled positive proportion of 51.8 percent (95 percent confidence interval, 43.8–59.7).

Positive faecal samples from 282 out of 443 patients (64 percent) remained positive for SARS‐CoV‐2 for a mean of 12.5 days (33 days maximum) after respiratory samples became negative for viral RNA.

SARS‐CoV‐2 viability was detected in five studies, in which six patients (6/17, 35 percent) had live active virus in their gastrointestinal specimens using Vero cell testing.

In light of the findings, the researchers urged that stool sample or anal swab testing be reconsidered in relation to decisions for isolating or discharging a patient.