Blood clotting may be root cause of long Covid-19 syndrome: Study

Patients with long Covid-19 syndrome continue to have higher measures of blood clotting, which may explain their persistent symptoms such as reduced physical fitness and fatigue, according to a study.

The symptoms of long Covid-19 syndrome, including breathlessness, fatigue and decreased exercise tolerance, can last weeks to months after the initial infection has resolved, and is estimated to affect millions of people worldwide.

The researchers from RCSI University of Medicine and Health Sciences in Ireland examined 50 patients with symptoms of long Covid-19 syndrome to better understand if abnormal blood clotting is involved.

Their study, published in the Journal of Thrombosis and Haemostasis, found that clotting markers were significantly elevated in the blood of patients with long Covid-19 syndrome compared with healthy controls.

These clotting markers were higher in patients who required hospitalisation with their initial Covid-19 infection.

However, the researchers also found that even those who were able to manage their illness at home still had persistently high clotting markers.

They observed that higher clotting was directly related to other symptoms of long Covid-19 syndrome, such as reduced physical fitness and fatigue.

Even though markers of inflammation had all returned to normal levels, increased clotting potential was still present in long COVID patients.

"Because clotting markers were elevated while inflammation markers had returned to normal, our results suggest that the clotting system may be involved in the root cause of long Covid-19 syndrome," said Helen Fogarty, the study's lead author, and PhD student at RCSI School of Pharmacy and Biomolecular Sciences.

Professor James O'Donnell, Director of the Irish Centre for Vascular Biology, RCSI noted that understanding the root cause of a disease is the first step towards developing effective treatments.

"Millions of people are already dealing with the symptoms of long Covid-19 syndrome, and more people will develop long Covid-19 as the infections among the unvaccinated continue to occur," O'Donnell said.

"It is imperative that we continue to study this condition and develop effective treatments," he added.