Colored scanning electron micrograph of a blood clot, showing red blood cells and platelets in a fibrin mesh.

‘Microclots’ could help solve the long COVID puzzle

Scientists are starting to detect clots in long COVID patients’ smallest blood vessels—which might help explain the condition’s debilitating symptoms.

A scanning electron microscope image provides a close view of a blood clot. The fibrous protein mesh incorporates tiny blood cell fragments called platelets (violet), which help the body form clots, and red blood cells that can also play an active role in clot formation and contraction. Large blood clots can block arteries or veins; microclots form in small blood vessels. 
Micrograph by Anne Weston/EM STP, the Francis Crick Institute, SCIENCE PHOTO LIBRARY
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