Long Covid may stem from an interaction between microclots and neutrophil extracellular traps, or NETs, in patients’ blood, potentially explaining persistent symptoms.

In the Journal of Medical Virology study, blood plasma from long COVID patients showed microclots that are not only more numerous but also larger compared with healthy controls.

Researchers observed NETs physically embedded within microclots in long COVID samples, a finding that could make clots more resistant to the body's fibrinolysis process.

Imaging flow cytometry and fluorescence microscopy were used on blood samples from 50 long COVID patients and 38 healthy volunteers across France and South Africa, revealing a consistent pattern.

An AI algorithm achieved 91 percent accuracy in distinguishing post-COVID samples from controls based on microclot and NET features, suggesting diagnostic biomarker potential.

The AI analysis, using anonymized samples, reinforces the diagnostic utility of microclot and NET signatures in identifying long COVID.

Previous findings note an increased risk of osteonecrosis of the hip after COVID-19 recovery, indicating broader potential post-recovery complications.

The findings point toward new treatment directions that target the vascular–immune axis rather than relying solely on antivirals for managing long COVID.

Researchers from Montpellier Cancer Research Institute and collaborators suggest the microclot–NET interaction could drive systemic changes contributing to long COVID symptoms.

Overall, the combination of microthrombi and NET structures could become the first objective biomarker for post-COVID syndrome, aiding diagnosis and understanding.