Research reveals that clear traces remain in the blood if the new coronavirus infection continues for a long time

The results of one of the UK's largest studies of patients hospitalized with SARS-CoV-2 infection show that long-term infections with the coronavirus develop inflammation that can be detected in the blood.

An analysis of more than 650 people hospitalized with severe coronavirus infections showed evidence of immune system activation in patients with prolonged symptoms. The exact pattern of this activation varied depending on the type of symptoms they had, primarily fatigue and cognitive impairment.

The research, led by Imperial College London, suggests that existing drugs that modulate the body's immune system could help treat long-term coronavirus infections and should be investigated in future clinical trials. Suggests.

Research published in journals innate immunologyis the latest research from two UK-wide collaborative consortia: PHOSP-COVID and ISARIC-4C. These involve Imperial scientists and clinicians, along with collaborators from the Universities of Leicester, Edinburgh and Liverpool, and are funded by UK Research and Innovation (UKRI) and the National Institute for Health and Care Excellence (NIHR). We are receiving offers.

Professor Peter Openshaw, Imperial National Heart and Lung Research Institute Principal Investigator, ISARIC-4C, said: “One in 10 SARS-CoV-2 infections will result in a long-term COVID-19 infection, with an estimated 65 million deaths worldwide. Diagnosis and treatment are currently very difficult as people suffer from ongoing symptoms.

“This study, which includes detailed clinical data on symptoms and a number of inflammatory plasma markers, is an important step forward and provides important insight into the causes of prolonged COVID-19 infection.”

runaway inflammation

In the latest study, researchers looked at a total of 426 people who were experiencing symptoms consistent with long-term COVID-19 infection and who had been hospitalized with COVID-19 at least six months prior to the study. did.

They were compared with 233 people who were also hospitalized with COVID-19 and made a full recovery. The researchers took plasma samples and measured a total of 368 proteins known to be involved in inflammation and regulation of the immune system.

They found that compared to patients who fully recovered, patients with COVID-19 showed a pattern of immune system activation indicative of inflammation of bone marrow cells and activation of a family of immune system proteins called the complement system. It turned out that

Bone marrow cells are formed in the bone marrow and produce different types of white blood cells that circulate in the blood and travel to organs and tissues that respond to injury or infection. The complement system consists of a cascade of linked proteins that are activated in response to infection or tissue damage. In particular, overactivation of the complement system is known to be associated with many autoimmune and inflammatory diseases.

Dr Felicity Liu, from Imperial's National Heart and Lung Institute, said: “Our findings demonstrate that complement activation and myeloid inflammation are common features of long-term COVID-19 infection following hospitalization, regardless of symptom type. This shows that it may be the case.”

“Finding evidence of continued complement activation months after an acute infection has subsided is unusual and suggests that long-lasting coronavirus symptoms are a result of active inflammation. But we don't know if this is true for all types of long-lasting coronavirus, especially if symptoms occur after an infection other than hospitalization.

Long-lasting new coronavirus subtypes

Researchers were also able to obtain comprehensive information about the different symptoms patients were experiencing and which symptoms were most common.

They found that certain groups of symptoms appear to be linked to specific proteins. For example, people with gastrointestinal symptoms had elevated levels of a marker called SCG3, which was previously thought to be associated with impaired communication between the gut and the brain.

Overall, there were five overlapping long-standing coronavirus subtypes with distinct immune signatures, despite some commonalities. Cognitive dysfunction; anxiety and depression. Cardiovascular function. And the stomach.

However, researchers stress that these groups are not mutually exclusive and people may move between groups depending on their symptoms.

Nevertheless, these long coronavirus subtypes appear to represent distinct biological mechanisms of the disease, highlighting that different symptoms may have different underlying causes. I'm doing it. The researchers suggest this could be useful in designing clinical trials, particularly treatments that target immune responses and inflammation.

One such treatment is drugs called IL-1 antagonists, such as anakinra, which is commonly used to treat rheumatoid arthritis, as well as drugs used to treat some types of cancer and severe rheumatoid arthritis. This may include another class of drugs called JAK inhibitors. Both drugs work by targeting components of the immune system that can be activated during prolonged COVID-19 infection.

The researchers highlighted that one of the limitations of the study was that it only included people who had severe SARS-CoV-2 infection and were hospitalized as a result. However, a significant proportion of people in the wider population who develop long-term COVID-19 infection will only report a mild initial SARS-CoV-2 infection, and it is unclear whether the same immune mechanisms are at work. It is unknown.

Professor Openshaw said: “This study provides strong evidence that long-term COVID-19 infection is driven by post-viral inflammation, but it also shows multiple layers of complexity. We hope that our research will pave the way for the development of specialized tests and treatments for various types of long-term COVID-19 infections and long-term infections.” We believe that a “one-size-fits-all” treatment approach may not work.

“COVID-19 continues to have far-reaching effects and affects many lives even after the initial infection has passed. Understanding this is the key to helping those affected.”

PHOSP-COVD and ISARIC4C are both funded by UK Research and Innovation (UKRI) and the National Institute for Health Research (NIHR), and both include partner institutions from all four UK countries.