Coronavirus particles

Saliva-based Covid-19 test is less intrusive and cheaper than PCR

Image credit: Science Photo Library

A less invasive Covid-19 test that uses saliva samples instead of the nasal and throat swabs used in current tests is being piloted at the University of Edinburgh.

The project, dubbed TestEd, uses an approach called hypercube sample to process dozens of saliva samples for PCR testing at once. The researchers believe the method will be able to save considerable time and money while maintaining accuracy compared to current tests.

While existing PCR tests are highly accurate, samples are normally taken at a test site and sent to a lab for individual analysis, which makes them costly.

They are aimed at people with symptoms so do not capture true Covid-19 rates in the community. Rapid lateral flow tests can be carried out at home by people with no symptoms, but are less accurate than PCR lab tests.

The new approach uses the same accurate lab analysis as the standard PCR tests, but saves money and resources by pooling samples while negating the need for swabs.

The study, which will offer all students and staff at the University twice-weekly testing, aims to detect infections before symptoms appear to assist in the safe reopening of campus.

If the system proves successful, organisers hope it could offer benefits beyond the University, in workplaces such as offices, schools and factories, which need access to regular testing.

TestEd recently won a £1.8m grant from the Medical Research Council, part of UK Research and Innovation, to scale-up its capacity to test staff and student volunteers and prove that its testing system works.

“The pandemic has been in a phase of relatively low levels of infection in the community, but cases are now increasing and Covid-19 remains a serious risk to health,” researcher Professor Jonathan Seckl said.

“Therefore having a non-invasive, accurate and affordable method to screen large groups of people in the workplace or centres of education is a high priority. TestEd offers the promise to provide just such a test with real advantages over the existing approaches. I recommend taking part in the study to all students and staff on a regular basis.”

Since the project began in January this year, more than 18,000 tests have been conducted, and it is hoped that half a million can be completed by the end of the year.

“The rise in cases caused by the Delta variant and the subsequent pause in the easing of restrictions are a timely reminder that we will be living with this disease for some time,”  said Professor Tim Aitman, TestEd’s chief investigator.

“Against this backdrop, TestEd addresses three key challenges of Covid-19 testing to keep workplaces safe: its ease of use makes it highly acceptable to people, its pooling of samples makes it affordable, and its use of PCR technology maintains high levels of accuracy.

“TestEd is a transformative approach for testing very large numbers for Covid-19 and for keeping organisations and communities safe.”

In January, another team demonstrated a Covid-19 testing method that uses a smartphone microscope to analyse saliva samples and can deliver results in around 10 minutes.

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