A cytokine biomarker should help identify patients suffering from long COVID, British researchers have announced.
A Cambridge University study has centred on two cytokines, produced by T cells in response to infection.
One cytokine is the best marker to date indicating whether someone has had COVID infection, the researchers say. A second is linked to long COVID.
The findings are early results from a study that so far has involved 85 COVID patients in Cambridge.
The research project hopes to involve 500 patients in total. It has been backed with £370,000 from the National Institute for Health Research, awarded to the University of Cambridge and Cambridge University Hospital NHS Foundation Trust.
Researcher Dr Mark Wills said: : “We need a reliable and objective way of saying whether someone has had COVID-19. Antibodies are one sign we look for, but not everyone makes a very strong response and this can wane over time and become undetectable.
“We’ve identified a cytokine that is also produced in response to infection by T cells and is likely to be detectable for several months – and potentially years – following infection. We believe this will help us develop a much more reliable diagnostic for those individuals who did not get a diagnosis at the time of infection.”
Fellow researcher Dr Nyarie Sithole said: “Because we currently have no reliable way of diagnosing long COVID, the uncertainty can cause added stress to people who are experiencing potential symptoms. If we can say to them ‘yes, you have a biomarker and so you have long COVID’, we believe this will help allay some of their fears and anxieties.
“There is anecdotal evidence that patients see an improvement in symptoms of long COVID once they have been vaccinated – something that we have seen in a small number of patients in our clinic. Our study will allow us to see how this biomarker changes over a longer period of time in response to vaccination.
“One of the theories of what’s driving long COVID is that it’s a hyperactive immune response – in other words, the immune system switches on at the initial infection and for some reason never switches off or never goes back to the baseline. As we’ll be following our patients for many months post-infection, we hope to better understand whether this is indeed the case.”
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