Leicester study finds long Covid leaves tell-tale traces in blood

A University of Leicester study has found that Long Covid leaves tell-tale traces in the blood. It also claims that existing drugs targeted at the immune system could help those left struggling with brain fog and crippling fatigue.

The PHOSP-COVID study, which was led by the National Institute for Health Research (NIHR) Leicester Biomedical Research Centre, looked at more than 650 people who had been hospitalised with severe Covid-19 and those with prolonged symptoms. The research found that their immune system had been activated, but the pattern depending on their symptoms which range from fatigue to cognitive impairment.

PHOSP-COVID, which is a partnership between the University of Leicester and the University Hospitals of Leicester NHS Trust, also found that Long Covid leads to ongoing inflammation which can be detected in the blood. It is a find that is thought to help tailor future responses and treatments to those still suffering.

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In the study, researchers included a total of 426 people who were experiencing symptoms consistent with Long Covid - these being people admitted to hospital with a Covid-19 infection at least six months prior to the study. They were compared with 233 people who were also hospitalised for the virus, but who had fully recovered.

The Leicester researchers, who also worked with Imperial College London and the universities of Liverpool and Edinburgh, took samples of blood plasma and measured a total of 368 proteins known to be involved in inflammation and immune system modulation. They found that compared to those who had recovered, Long Covid sufferers showed a pattern of immune system activation indicating inflammation of myeloid cells. These cells are formed in the bone marrow and produce various types of white blood cells that circulate in the blood and migrate into organs and tissues where they respond to damage and infection.

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NIHR Senior Investigator and Clinical Professor in Respiratory Medicine at the University of Leicester, Chris Brightling, said: “This study is a real step-forward in our understanding of Long Covid. Finding different patterns of inflammation in people with Long Covid that are suffering with different constellations of symptoms tells us we are getting closer to discovering the drivers of long-COVID that will respond to targeted therapy.”

The research also looked into the specific symptoms of Long Covid and found that certain groups of symptoms were all associated with specific proteins. It uncovered that those with gastrointestinal symptoms had increased levels of SCG3 - a protein linked to impaired communication between the gut and the brain.

Overall, five subtypes of Long Covid symptoms were found - fatigue; cognitive impairment; anxiety and depression; cardiorespiratory; and gastrointestinal. However, researchers said that these overlapped and some people suffered from multiple subtypes, while their investigations suggested that existing drugs which modulate the body’s immune system could help treat Long Covid. Researchers said this finding should be investigated in future clinical trials.

Professor Peter Openshaw, from Imperial College London’s National Heart & Lung Institute, said: “We hope that our work opens the way to the development of specific tests and treatments for the various types of Long Covid and believe that a ‘one size fits all’ approach to treatment may not work.

“Covid-19 will continue to have far reaching effects long after the initial infection has passed, impacting many lives. Understanding what’s happening in the body, and how the immune system responds, is key to helping those affected.”