A blood test taken shortly after infection with the SARS-CoV-2 virus could single out those most likely to suffer from symptoms of long COVID, a study carried out at University College London has found.


The finding could help healthcare workers to prescribe antiviral drugs during the initial stage of infection in an attempt to reduce the risk of patients developing long COVID, the researchers say.

To make the discovery, the researchers analysed blood plasma samples taken from more than 150 healthcare workers using mass spectrometry once a week for six weeks. Of these, 54 had tested positive for COVID-19 on PCR tests and 102 had tested negative.

Under normal circumstances, protein levels in the body remain stable. However, the researchers found dramatic differences throughout the six-week period in the proteins of those who had tested positive for COVID-19. Moreover, larger disruptions in the proteins were correlated with more severe symptoms.

Of the 54 participants who tested positive, 11 reported at least one persistent symptom consistent with long COVID one year after infection. The team found that these participants had displayed abnormal levels of 20 specific proteins in their initial blood plasma samples. Most of these proteins are involved with anti-coagulant and anti-inflammatory processes.

“Our study shows that even mild or asymptomatic COVID-19 disrupts the profile of proteins in our blood plasma. This means that even mild COVID-19 affects normal biological processes in a dramatic way, up to at least six weeks after infection,” said lead researcher Dr Gaby Captur of the MRC Unit for Lifelong Health and Ageing at UCL.

As the method used in the study can analyse thousands of samples in an afternoon, it could be offered alongside PCR tests to predict a patient’s likelihood of developing long COVID, the researchers say.

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“Our tool predicting long COVID still needs to be validated in an independent, larger group of patients," said Captur.

"However, using our approach, a test that predicts long COVID at the time of initial infection could be rolled out quickly and in a cost-effective way.”

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Jason Goodyer
Jason GoodyerCommissioning editor, BBC Science Focus

Jason is the commissioning editor for BBC Science Focus. He holds an MSc in physics and was named Section Editor of the Year by the British Society of Magazine Editors in 2019. He has been reporting on science and technology for more than a decade. During this time, he's walked the tunnels of the Large Hadron Collider, watched Stephen Hawking deliver his Reith Lecture on Black Holes and reported on everything from simulation universes to dancing cockatoos. He looks after the magazine’s and website’s news sections and makes regular appearances on the Instant Genius Podcast.