We don’t know exactly how many people have been infected with the coronavirus due to a lack of comprehensive testing, but we could begin monitoring about 2 billion people worldwide right now, simply by looking for the pathogen in waste water.
“It feels like a no-brainer: everything is in place to do this,” says Rolf Halden at Arizona State University. “You could get a huge return on your investment and save many lives.”
The monitoring would be a fraction of the cost of traditional clinical testing, and in the right circumstances could detect one person carrying coronavirus among a healthy population of 2 million.
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Researchers around the world have been . In 2013, for instance, the approach .
At the start of the year, there were concerns that the technique wouldn’t work with coronavirus because its RNA would readily fall apart. But published in confirm that coronavirus can, after all, be . This suggests it can survive in waste water too.
“I have a tonne of emails telling me it’s impossible,” says Halden. “But now it’s been shown to be possible and everyone wants to get involved.”
Waste water coronavirus testing could be performed using essentially the same techniques now being used to test individuals. Halden and his colleague Olga Hart have run the numbers to get a sense of how sensitive the approach could be.
Depending on local factors, including the temperature of the waste water and the size of the sewerage system, it should be possible to detect coronavirus in sewage if just one in every 114 of the people using the sewerage system is infected.
In ideal situations where, for instance, the waste water is cool enough to preserve viral RNA, Halden and Hart estimate that waste water testing could detect coronavirus even if just one person in 2 million is infected.
Although such testing won’t tell you who is infected, it will reveal which towns – or even which districts within a town – are home to carriers. Halden says this would then allow for more targeted testing of individuals.
“It sounds like an economic way to get a broad understanding of how widespread the disease is,” says Rolf Lood at Lund University, Sweden. He is more cautious about Hart and Halden’s figures, because some individual carriers shed up to 200 times more virus than others, but as a quick test to determine how widespread the disease is on a regional scale, he sees the benefits.
Waste water testing could expand our ability to monitor coronavirus and other public health threats globally through existing infrastructure, says Halden. He created the a few years ago, which already monitors waste water samples representing about 250 million people around the world. There are initiatives at other institutions.
“The numbers I’m crunching show you could begin to analyse 2 billion people for coronavirus right now,” says Halden. “To get the economy back on an even keel, we have to monitor and manage the virus in every country, and do so quickly and economically. That’s something we can help do with this approach.”
Science of the Total Environment
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