Researchers find important biomarkers in long COVID

During Almedalen Week, Jonas Bergquist presented new research findings at the seminar “The post-infectious elephant in the room”. Among those present were the Swedish Covid Association and the National Association for ME Patients.

Both ME and long COVID are multifactorial diseases and the patient population is growing. Bergquist’s research focuses on understanding why some patients develop long-term symptoms after recovering from an infection.

“We look at biomarkers, that is, markers of changes in the body’s chemistry and, in my case, especially in the chemistry of the brain,” explains Bergquist, Professor of Analytical Chemistry and Neurochemistry at Uppsala University.

Inflammation markers in cerebrospinal fluid and blood

The research group has made two important discoveries. First, they found neuroinflammation markers in the cerebrospinal fluid surrounding the brain in patients with ME. Then, together with partners, the team published an article on long COVID patients. Inflammation markers were also found in this group of patients, but this time in the blood as well. The article was published in May 2025 and offers new hope for long COVID patients.

How can your research results be used?

“The idea is to understand why people get this disease but also how to diagnose it correctly. After all, many of the symptoms can overlap with other underlying diseases. We also want to access treatment strategies. If we understand what has gone wrong in the body, we can attack these systems with drugs or other types of treatment.”

The findings provide important clues about what happens in the body when patients develop long-term problems after infections.

Clinical study with Harvard

In parallel with the basic research, a clinical research study is in progress in collaboration with Harvard. The study involves 160 ME patients who are being studied in depth and given the opportunity to participate in treatment trials.

The patients are divided into four groups: one receives a placebo, one receives a low dose of the medicine naltrexone, which treats pain and inflammation in the brain. A third group receives mestinon, a medicine that affects blood pressure regulation and inflammation, and the fourth group receives both medicines in combination. It is the latter treatment that researchers believe in most.

“We hope the results will show that it really is an effective treatment for the vast majority of patients,” says Bergquist.

Lack of knowledge in primary care

The research has the potential to develop both diagnostic methods and treatment strategies. However, one challenge is the lack of knowledge in primary care, which is often the first point of contact for patients with long COVID and ME.

“It is of course primary care that is the interface with the patient population and in general, primary care has not had time to familiarise itself with the problems of the long COVID population, nor with the ME population earlier,” Bergquist notes.

Having said that, there is great interest in learning more. Bergquist receives many calls every week from primary care and carers seeking help and support with treatment and diagnostics.

“But we need to do even more. We need to go out and educate more. We also need stronger platforms for collaboration between research and treatment and clinical practice,” he says.

Annica Hulth