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Long COVID has baffled doctors for years, but new research may have uncovered a crucial clue: microscopic clots tangled with immune system debris in patients’ blood.
Scientists discovered that people suffering from long COVID had significantly more of these unusual structures-nearly 20 times higher-than healthy individuals.
The clots, embedded with neutrophil extracellular traps (NETs), are like sticky webs released by immune cells. For the first time, researchers have seen these microclots and NETS physically linked, suggesting a novel biological marker that may help explain persistent symptoms.
Why does it matter? These strange clots could block blood flow in the smallest vessels, reducing oxygen delivery to organs and potentially fueling symptoms like brain fog, fatigue, and shortness of breath.
Even more promising, an Al system trained to recognize these structures could diagnose long COVID with 91% accuracy, offering hope for a future test. Though still in early stages, the study marks a critical step toward unlocking the mystery behind one of COVID-19’s most lingering legacies.
Source: “Circulating Microclots Are Structurally Associated With Neutrophil Extracellular Traps and Their Amounts Are Elevated in Long COVID Patients.” Journal of Medical Virology, 2025.