Blood clotting dysfunction identified as key factor in long COVID

Scientists have identified specific blood abnormalities in long COVID patients that may explain the condition's debilitating symptoms, according to research published in the Journal of Medical Virology. The study reveals a potentially crucial mechanism involving microscopic blood clots and altered immune responses that could underlie the persistent fatigue, cognitive impairment, and physical discomfort reported by millions worldwide.

Key Biological Markers Discovered

The research team found significantly elevated levels of two interconnected biomarkers in long COVID patients: microscopic clots known as "microclots" and neutrophil extracellular traps (NETs) released by white blood cells. These microclots were not only more numerous but also larger in patients compared to healthy volunteers, while NETs—normally deployed to trap pathogens—appeared dysregulated and potentially contributing to the clotting phenomenon.

Pathological Interaction and Symptoms

Researchers discovered that neutrophils in long COVID patients undergo changes causing them to expel DNA and enzymes that form NETs, which then interact with microclots in what study co-author Alain Thierry described as "underlying physiological interactions between microclots and NETs that, when dysregulated, may become pathogenic." The study suggests that "higher NETs formation might promote the stabilisation of microclots in circulation, potentially leading to deleterious effects which contribute causally to the long Covid syndrome."

Clinical Implications and Treatment Pathways

This dysfunctional interaction between clotting factors and immune cells may cause widespread inflammation and impede proper blood flow to organs and tissues, potentially explaining common long COVID symptoms. The findings offer new directions for targeted treatments, including approaches focused on reducing microclot formation or limiting NET activity, potentially providing relief for patients experiencing the condition's characteristic fatigue, brain fog, and breathlessness months after initial infection.