Saliva tests could help meet Boris Johnson's 24-hour target

A new saliva test for coronavirus could help ministers to meet Boris Johnson's 24-hour target for showing whether a patient has the disease.

The Government is in talks with a British firm about rolling out a test that would involve suspected Covid-19 patients spitting into a tube and posting the sample to a lab.

One expert involved with the project said the firm was aiming to produce test results within one hour of the samples arriving at labs.

The disclosure comes after the Prime Minister promised that by the end of the month the majority of test results would be produced within 24 hours.

Health officials have been holding talks with Chronomics, a firm producing a saliva test which could be examined at many more labs than swab tests  because the tube contains a solution that "inactivates" the virus.

Under government rules, live samples of the virus can only be examined by labs with highly specialised equipment that confirms to its highest "containment level".

Philip Beales, a professor at the University College London Institute of Child Health, who has been helping to coordinate the efforts of smaller firms such as Chronomics and Nonacus, which developed the test, said:  "The saliva test has this inactivation buffer in the bottom, which inactivates the virus, preserves the RNA and then in thousands of [labs] in the country, you can just do a straightforward RNA extraction."

He added: "Our guys are working on a one hour turnaround time from receipt of the sample in the lab, to getting the actual result back."

Chronomics is understood to be carrying out a final study with Public Health England to validate its saliva kits, while it holds discussions with officials about providing the tests for use in the NHS and as part of the Government's mass testing programme.

Last month, at a Downing Street press briefing, Matt Hancock, the Health Secretary, disclosed that the Government was "working with many top names to help us deliver testing with a rapid turnaround - names like Oxford Nanopore and Chronomics." Prof John Newton, the Government's testing tsar, has said: "The saliva testing is a really interesting one... So we are actively looking at those and we are engaging with the companies and if they prove to be better then we will use those."

The Chronomics test would involve patients spitting sputum - the mixture of saliva and mucus coughed up during the illness - into a tube provided to them in hospital or sent to their homes. The sealed tube would then be sent to a lab for testing.

In late April a Yale study suggested that new saliva tests were a "more sensitive" alternative to the swab tests currently administered across the UK. Researchers said saliva was a "viable and more sensitive alternative" to nose and throat swabs, partly because such tests can be more reliably carried out by patients at home. Some doctors fear that many patients fail to take an adequate samples of viral RNA, or ribonucleic acid, from their nose or throat, leading to false negative results.

The apparent sensitivity of the saliva tests has led to optimism that workplace testing of asymptomatic staff could become routine, with samples handed to office managers or human resources staff to send to labs. The Sunday Telegraph first reported on the tests in April, when Prof Beales criticised Public Health England for being too slow to provide RNA samples from Covid-19 positive patients to help validate the emerging saliva tube tests.

Yesterday, experts warned that coronavirus tests taking longer than 48 hours to provide results risked rendering the track and trace system useless.

Up to 20,000 coronavirus tests a day are taking longer than two days to provide results. Scientists advising the Government on track and trace predict this could lead to a 50 per cent increase in the number of infections. The contacts of a person with Covid-19 are only notified when a positive test result is returned

Dr David Bonsall, from the University of Oxford’s Nuffield Department of Medicine and a scientific advisor to the NHSX app programme, said that speed is essential.