Sewage tunnel

Sewage-based coronavirus surveillance trials begin

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Scientists have started conducting tests at 44 wastewater treatment sites in an effort to develop a system to monitor wastewater for traces of the novel coronavirus.

Sewage surveillance – which is already used to monitor wastewater for polio – involves examining human waste for signs of disease, such as viral genetic material. Although the WHO has said that there is not currently evidence that the novel coronavirus can be transmitted via sewage systems, tests have been able to detect the genetic residues of the virus in wastewater due to infected people shedding the virus in their faeces.

Last month, it was reported that UK scientists are working on a standardised system to detect coronavirus in wastewater as part of the £1m National Covid-19 Wastewater Epidemiology Surveillance Programme. The scientists also plan to assess whether the presence of viral residue in wastewater may be able to cause transmission to sewage workers.

Now, the Department for the Environment, Food, and Rural Affairs (Defra) has confirmed that trials to detect signs of the coronavirus in wastewater have begun at 44 wastewater treatment sites in England. The government is working with scientists, water companies and devolved governments on the trials.

Scotland is carrying out its own trial to search for signs of the coronavirus in sewage.

Environment secretary George Eustice said that the research would hopefully give the government a “head start” on where new outbreaks were likely to emerge.

The UK Centre for Ecology and Hydrology’s Dr Andrew Singer – who is working on a standardised test for viral material from wastewater samples – told BBC News, “We would like to have confidence in saying that when we have an increase in virus numbers in the sewage from week to week, there are higher numbers of coronavirus cases. This means we will be able to look for trends […] to see if the release from lockdown maintains infection levels or are things moving in the wrong direction.”

Singer added that sewage epidemiology is a “messy science” due to the vast number of contaminants in wastewater.

Research has suggested that wastewater sampling could provide signs of a local coronavirus outbreak up to a week earlier than standard medical testing. Testing wastewater could also allow for viral hotspots to be identified even when people infected by the virus are mostly asymptomatic or unable to access tests.

Several other countries, including Spain, have started to monitor their wastewater in an effort to better understand outbreaks of Covid-19 in the community. A similar study in the US is assessing solid samples, as previous research suggests that the coronavirus may stick to wastewater solids more than other viruses.

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