Vital study into coronavirus transmission


Scientists from the University of Leeds are to study live virus excretion in faeces to understand more about the spread of SARS-CoV-2 – the coronavirus responsible for the pandemic.

The Leeds team will test stool samples in order to establish whether live, transmissible virus is present, and for how long this might be the case. 

This study has major implications.

Dr Kerrie Davies, Principal Clinical Scientist

“This study has major implications in terms of transmission, environmental contamination, how patients are managed, how we handle samples and how we control the hospital environment,” said Principal Clinical Scientist Dr Kerrie Davies, from the School of Medicine at the University of Leeds, and Leeds Teaching Hospitals NHS Trust.

The study is funded by the Jon Moulton Charity Trust which was interested in the wide-ranging implications of an investigation into transmission.  

Clinical trials are selected based on high-quality science with the potential to have a direct benefit to patients.

Jon Moulton, Jon Moulton Charity Trust

“Clinical trials are selected based on high-quality science with the potential to have a direct benefit to patients,” explained Mr Moulton. 

The Charity Trust aims to make clinical advances and promote the relief of suffering, and the team’s proposal fits the criteria perfectly. 

The investigation follows findings which suggest an additional pathway of transmission for COVID-19 beyond respiratory droplets.  

“A few studies have detected SARS-CoV-2 virus RNA in faecal samples,” Dr Davies said. “They’ve established that the RNA can be seen for quite a while.” 

In some cases, the RNA was present in patients who had returned negative respiratory samples, although this does not give the full picture.

Dr Davies explained: “Just because you can detect the RNA in faeces, it doesn’t mean that it is live or transmitted.

“We’re looking to find out whether there is live virus in the stool of patients, and for how long. If there is live virus, then there is the potential for it to be a source of transmission.” 

Such transmission would come through faecal-oral routes, which is often a result of poor hygiene practice such as failing to close the lid when flushing the toilet, which can create a plume of organisms.  

If transmittable RNA is present in stool, even after a negative respiratory test, it might mean that current protocol is insufficient.

Dr Davies said: “Current guidance states that a healthcare worker who has tested positive for COVID-19 can return to work after 7 days if they are symptom-free.

“However, we don’t know if they are still excreting the virus at that point, in which case what we’re doing might not be good enough infection prevention and control. We're aiming to recruit our first patients within the next week.” 

As part of the study, NHS staff will also be included in the sample.

In future, using the same study samples, further investigation may be possible into the microbiomes – organisms inside the human gut – of positive and negative patients, which could have therapeutic implications should there be significant differences. 

As such not only will this work help to influence national guidance on COVID-19 protocol in patients and healthcare workers, it may play a role in treatment of the virus going forward.

For further details contact Prue Griffiths, University of Leeds press office, via