A key aspect of the covid-19 pandemic has been the amount of testing conducted around the world. There has been unprecedented demand for testing over the last one year. The most widely used approach for testing requires a polymerase chain reaction or PCR test, which involves taking a swab of the back of the throat and far inside the nose or nasal swabs.
Now, researchers at the University of Surrey have demonstrated that non-invasive skin swab samples may be enough to detect the novel coronavirus quickly, according to a study published earlier this month in the Lancet E Clinical Medicine journal.
For the study, chemists from Surrey partnered up with Frimley NHS Trust and the universities of Manchester and Leicester to collect samples of sebum -- a waxy, oily substance produced by the body's sebaceous glands that are located on the face, neck or back -- from 67 hospitalised patients, 30 who had tested positive for covid-19 and 37 who tested negative.
These samples were collected by gently swabbing the skin area. The team then analysed the samples by using liquid chromatography-mass spectrometry, a technique that looks for residual chemical compounds, and a statistical modelling technique to differentiate between the covid-19 positive and negative samples, an official release explains. The researchers found that patients with a positive covid-19 test had lower lipid levels -- known as dyslipidemia -- than their counterparts who had tested negative. They also noted that the accuracy of the findings increased further when medication and additional health conditions were controlled.
“Our study suggests that we may be able to use non-invasive means to test for diseases such as covid-19 in the future -- a development which I am sure will be welcomed by all,” Melanie Bailey, co-author of the study from the University of Surrey, explains in the release.
Matt Spick, co-author of the study from the University of Surrey, said that covid-19 damages many areas of metabolism. Keeping that aspect in mind, the sebum sampling could not only help with detecting the covid-19 virus but also its effect on the host’s metabolism. “In this work, we show that the skin lipidome can be added to the list, which could have implications for the skin's barrier function, as well as being a detectable symptom of the disease itself," Spick said.
Investigating new methods of diagnosis and surveillance in a new disease such as covid-19 that has had such a devastating effect on the world is vital, George Evetts, consultant in anaesthesia & intensive care medicine at Frimley Park Hospital, said in the release. “Sebum sampling is a simple, non-invasive method that shows promise for both diagnostics and monitoring of the disease in both a healthcare and a non-healthcare setting," Evetts added.
Some other recent developments have brought out interesting aspects of covid-19 testing. New data from researchers at Vanderbilt University suggests that the accuracy of throat swab tests may vary by time and day. Researchers analysed 31,094 tests performed in symptomatic and asymptomatic individuals at 127 testing sites, including 2,438 tests that showed covid-19, according to Reuters report. In a paper posted on Saturday on medRxiv ahead of peer review, the researchers reported that tests were most likely to be positive around 2 pm - and the proportion of positive tests in the early afternoon was twice as high as the lowest proportion seen at other times of the day.
The study “suggests people may be more contagious at certain times of the day and it raises questions about whether tests for SARS-CoV-2 may be less accurate when they are collected between late evening and early morning," said co-author Candace McNaughton of Vanderbilt University. "If our findings are confirmed, clinicians and public health teams could focus their efforts on lowering the risk of viral spread during times of peak viral shedding," she said.
(With inputs from PTI)