New research by a team at the University of Surrey has found skin swabs are “surprisingly effective” at identifying Covid infection. As part of the study they used non-invasive swabs to collect sebum – an oily waxy substance produced by the body’s sebaceous glands – from 83 hospitalised patients, some of whom had coronavirus. They also took blood and saliva samples to analyse and compare.
COVID-19 has been found to significantly change the makeup of lipids (fats and oils) of biofluids such as blood or sebum.
By measuring changes in lipids and other metabolites of the samples, the researchers observed that – with a 1.0 score being the most accurate and sensitive – skin swab tests scored 0.88.
While blood samples scored 0.97 and saliva tests scored 0.80.
Professor Melanie Bailey, co-author of the study, explained: ”COVID-19 has shown us that rapid testing is vital in monitoring and identifying new illnesses. In our research, we explored the relationships between different biofluids, and what changes in one part of the human body can tell us about the overall health of a patient.
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“Our results show that, while blood is the most accurate way of testing for this virus, skin swabs are not too far behind – in fact, the skin swab results were surprisingly accurate.”
Research student and co-author, Matt Spick, co-author and research student at the University of Surrey, added: “Our research suggests that skin sebum responds to changes to the immune system in COVID-19 patients.
“In fact, we believe that illness can alter the body’s natural balance across the whole range of biological systems, including skin, digestive health and others.
“This can help us identify and understand illness better by providing a whole-body atlas of a disease.”
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In comparison, PCR (polymerase chain reaction) tests work by searching for a small genetic fragment of the Covid virus.
The fewer cycles it takes to find the virus, the stronger the infection.
PCR tests can pick up tiny amounts of the virus, meaning someone can test positive before they even become infectious.
And the line on a lateral flow test is made up of antibodies that can bind to the Covid virus, meaning it will show up if the person is infected.
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Co-author and section lead of chronobiology at the University of Surrey, Professor Debra Skene, said the new findings were a reason to “rejoice”.
“The work we demonstrate in this study that profiles metabolites in three different biofluids (serum, saliva and sebum) offers promise in distinguishing people positive for COVID-19 from people negative for COVID-19,” she said.
“The promise of a non-invasive test for Covid-19 is a reason for much of society to rejoice.”
It comes as there were 174,961 new Covid cases recorded in England in the week up to July 8.
This means 309.4 people out of every 100,000 tested positive.
In Scotland there were 17,812 new cases, or 325.9 out of 100,000 people.
There was no separate data for Wales and Northern Ireland but since the start of the pandemic there have been 22.2m cases of Covid throughout the UK.
The research has been published in the Scientific Reports journal.
