Saliva tests for the coronavirus would be easier to do than swab tests (pictured)
A city in the UK is about to start testing thousands of people for the coronavirus each week, using easily collected saliva and a cheap, quick way of detecting the virus. If the initial trial in Southampton is successful, the aim is to test the city’s entire population of 250,000 people every week to see if this can rapidly halt the virus’ spread.
“We were told there were insoluble aspects, but they have been solved,” says Keith Godfrey at the University of Southampton, who is helping organise the trial. “The government is certainly seriously interested.”
It has been proposed that weekly testing of a country’s entire population, regardless of whether people have symptoms or not, could quickly bring coronavirus outbreaks to an end, with the resulting economic benefits far outweighing the costs of mass testing. Advocates of the approach include Julian Peto at the London School of Hygiene & Tropical Medicine and economist Paul Romer in the US.
On 10 April, an open letter to senior UK politicians and scientific advisers signed by Godfrey, Peto, Romer and 31 others called for weekly universal testing to be trialled in a small city. The Southampton scheme is a first step towards this.
The initial study in Southampton will begin with doctors and members of their households, and be expanded to include council workers and university staff and students, with more than 10,000 tests being done each week.
It will look at whether testing saliva works as well as taking swabs from the nose and throat, the method currently used to test for the coronavirus. Taking swabs is difficult, unpleasant and unreliable, producing many false negatives. By contrast, providing a saliva sample is as easy as spitting. People can do it at home and send samples off for testing, and some unpublished studies suggest that saliva testing is more reliable.
If this proves to be the case, it would be much easier to do mass swab-testing. For instance, children attending school could be tested weekly. “Here we have a test that would be acceptable to children,” says Godfrey.
The study is also using a method of detecting the virus called RT-LAMP, which is much quicker and cheaper than the standard PCR method. It involves little more than adding a sample to a clear tube containing the necessary chemicals, putting it in a water bath to warm it and seeing if the colour changes.
“You don’t need highly qualified staff,” says Peto. “Anyone can stick something in a water bath.”
Working with the National Health Service, the local council and the university, Godfrey and his colleagues have also developed home saliva-collecting kits, ways of getting them to and from people and IT systems for quickly telling people their results by text. The trial is also integrated with the UK’s contact-tracing system.
If the trial is successful, Godfrey wants to expand it to everyone in the city. “We are doing the pilot as a potential stepping stone to that,” he says.
The idea of mass testing has been dismissed by many as infeasible, says Peto. But between 14 and 24 May, China tested 9 million people in Wuhan. The tests identified around 300 people with asymptomatic infections and seem to have helped prevent a resurgence of covid-19 in the area.
“It’s certainly an option worthy of exploration,” says Clare Turnbull at the Institute of Cancer Research in the UK. She, Peto and others published an analysis today suggesting that weekly testing of an entire population, along with contact tracing and strict quarantine of households where people are infected, could stop transmission within a few weeks. But the only way to confirm this is to try, says Turnbull.
Article amended on
25 June 2020
We have corrected the city status of Southampton
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