Sewage tests may be key to detecting clusters

Areas requiring lockdown could be given five-day advantage if virus is found in water, US scientists say

‘Many people will not know they have it at all. Those are the ones that wastewater testing is going to pick up’

TESTING sewage could predict local coronavirus outbreaks five days before they happen, scientists have found.

The team from Yale University found that the detection of the viral strain of Covid-19 in sewage leads to hospital admissions in an average of 4.6 days.

They say their model provides an earlier indication of where coronavirus is growing in the community than data from hospital admissions. Such an advance in the UK could lead to much quicker identification of the coronavirus, meaning the Government can act quicker to lock down affected areas, experts say.

Brian Neve, a process control engineer and non-executive director of technology company Spiro Control, said that trials such as the Yale one show that wastewater epidemiology should be used as an early warning.

He added: “Some of them are confident about prediction numbers and hence indicate that it can be used for policy decisions.

In future, better and more upstream wastewater sampling could result in even faster detection, further reducing the delays.”

Work has been quietly going on in this field since March in the UK, with the Department for Environment, Food and Rural Affairs leading the effort in sampling at 44 sites across England.

Their hope is these data will feed into the Covid-19 alert system, alongside local testing, and allow for the Government to act swiftly in its “whack-a-mole” local lockdowns.

Where water sampling comes into its own is its ability to detect those carriers of the virus who are asymptomatic and pre-symptomatic – one of the major obstacles in the Government’s current testing programme.

Dr Alex Corbishley, who is leading research at the University of Edinburgh’s Roslin Institute, told The Sun

day Telegraph it is suspected some carriers are infectious before they show clinical signs, and these people could be found early by sewage testing.

“The testing of the population is heavily biased to those with clinical signs,” he said. “But we know children in particular and most people under the ages of 30 to 40 are at very low risk of clinical signs.

“Many people will get it and not know they have it at all. Those people are the ones wastewater testing are going to pick up before you get people in a hospital.

“You have parts of the population transmitting the virus and they don’t know that they’re doing it, but this could spill over into higher risk people and cause them to be sick, which then causes hospital admissions.”

The sewage method has been used for three decades to estimate where polio is circulating, how serious the outbreak is, and where it has come from. The hope is it can now be used as an integral part of the UK testing network, even helping with outbreaks of flu.

“This is one tool in the toolbox and we need as many tools as we can. The challenge is: how do you monitor 66million people?” says Dr Corbishley.

He added: “To continually monitor that many people only on symptoms is unreliable, as we have a significant number of people that don’t display symptoms. Going into the autumn, there are other uses for this.

“One concern is how influenza interacts with coronavirus and now we will be able to see if we can find them together in communities.”