Wastewater could hold the key to identifying Covid-19 hotspots

While no standard methods have been established for detecting the virus in wastewater so far, the Water Research Foundation (WRF) said that environmental surveillance of sewersheds holds “significant promise” for determining Covid-19 trends in different communities.

Such a technique has its own challenges, as the virus’ genetic markers can easily get lost or diluted amongst the flow of sewage. Water treatment plants also impact the signal.

The WRF is looking at how data about the levels of the virus in wastewater can be used to create trends and estimates about how it may spread in the future in order to inform policy decisions.

Professor Vanessa Speight, from the University of Sheffield, which is collaborating with the WRF, is researching techniques to reliably interpret the data collected from sewage samples.

Her results could help create a more accurate map of how the virus is spreading and show the emergence of a second wave of the pandemic.

“There is great potential for waste water to provide valuable information about the occurrence of Covid-19 across communities,” she said.

Further research is being carried out into how samples can be preserved for analysis without exposing wastewater workers to the disease.

The WRF is looking into techniques such as heating the samples or adding chemicals to deactivate the potentially live virus. It is also looking at how storing samples at different temperatures affects the viral load.

On Monday, Prime Minister Boris Johnson said a new alert system to monitor the threat posed by coronavirus could eventually identify local flare-ups if Covid-19 is detected in the waste water from a local area.

The PM’s official spokesman said: “Some studies have been carried out overseas on this and I think it is something we are looking at as a possible way of seeing if you could track the rate of infections locally.”

The Downing Street spokesman said officials are investigating whether sewage samples would allow them to “track if the virus is more prevalent in some parts of the country than in others”.

A spokesman from the Department for Environment, Food and Rural Affairs (Defra) said: “We are actively engaging with the research community and Government scientific advisers to investigate whether monitoring waste water could be used as a way of tracking the prevalence of the virus.”