Long COVID Study Suggests Immune System at Root of Symptoms

Scientists may be on the path to understanding long-term COVID after identifying changes in blood proteins found in people with long-term symptoms of the virus.

A study published in the journal Science, January 18, found that patients who experienced long-term COVID symptoms had proteins indicating that part of their immune system remained active after infection.

According to experts, the discovery could lead to diagnostic tests and treatments for long-haul COVID, which causes people to experience persistent fatigue, brain fog, chest pain, stomach problems and a variety of other symptoms.

The study focused on 113 COVID patients and 39 healthy controls. After six months, 40 patients had developed long-term COVID characteristics.

Blood samples for those patients contained a cluster of proteins that showed the body’s complement system, part of the immune system, remained on high alert long after the COVID virus emerged.

When the complement system remains active without any resistance to COVID, it “starts to damage healthy cells,” according to Dr. Onur Boyman, a professor of immunology at the University of Zurich in Switzerland and one of the authors of the study.

Blood samples from long-term COVID patients showed a common group of proteins indicating increased immune system response.Blood samples from long-term COVID patients showed a common group of proteins indicating increased immune system response.

According to experts, tissue damage and microclots in the blood can reduce the level of oxygen and nutrients delivered to various organs, thereby causing prolonged COVID symptoms.

“If your brain, for example, doesn’t get enough oxygen, obviously there’s going to be a lot of problems with memory, brain fog, and fatigue,” Akiko Iwasaki, professor of immunobiology, and molecular, cellular, and developmental biology at Yale School of Medicine, told NBC News.

Monica Verduzco-Gutierrez, chair of rehabilitation medicine at the University of Texas Health Science Center at San Antonio and head of the long-term COVID clinic, told NBC News that the research represents a major advance in the study of the virus.

“Understanding the long-term mechanisms of COVID is how we find treatments,” he said.

About 14% of adults report experiencing long COVID, according to data from the US Census Bureau’s Household Pulse Survey.

Read the full study in Science here.

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