Blood test when people are infected ‘can predict who will develop long COVID’

A simple blood test taken when people are infected with COVID-19 could predict who is likely to suffer from ‘Long COVID’, a new study has suggested.

Proteins in the blood of infected people offer a ‘signature’ which predicted accurately whether they would go on to develop ‘Long COVID’.

Long COVID is a syndrome in which complications persist more than four weeks after the initial infection of COVID-19, sometimes for many months.

Researchers analysed proteins in the blood of health care workers infected with SARS-CoV-2, cand compared them to samples from health care workers who had not been infected.

Usually protein levels in the body are stable, but the researchers found a dramatic difference in levels of some of the proteins up to six weeks following infection, suggesting disruption to a number of important biological processes.

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Using an artificial intelligence (AI) algorithm, they identified a “signature” mix of proteins, associated with Long COVID

Lead author Dr. Gaby Captur (MRC Unit for Lifelong Health and Ageing at UCL) said, "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.

"Our tool predicting long COVID still needs to be validated in an independent, larger group of patients. 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. The method of analysis we used is readily available in hospitals and is high-throughput, meaning it can analyze thousands of samples in an afternoon."

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Senior author Dr. Wendy Heywood of UCL Great Ormond Street Institute of Child Health and Great Ormond Street Hospital said, "If we can identify people who are likely to develop long COVID, this opens the door to trialing treatments such as antivirals at this earlier, initial infection stage, to see if it can reduce the risk of later long COVID."

Researchers used blood plasma samples from 54 health care workers who had PCR- or antibody-confirmed infection, taken every week for six weeks in spring 2020.

They compared them to samples taken over the same period from 102 health care workers who were not infected.

They used targeted mass spectrometry, a form of analysis that is extremely sensitive to tiny changes in the amount of proteins in blood plasma, to look at how COVID-19 affected these proteins over the course of six weeks.

The researchers found abnormally high levels of 12 proteins out of the 91 studied among those infected by SARS-CoV-2, and that the degree of abnormality tracked with the severity of symptoms.

The research team found that at the time of first infection, abnormal levels of 20 proteins studied were predictive of persistent symptoms after one year. Most of these proteins were linked to anti-coagulant (anti-clotting) and anti-inflammatory processes.

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