‘Hyperactive’ platelets behind mysterious blood clotting in COVID-19 patients

Depiction of a blood clot forming inside a blood vessel

Inflammatory proteins made during SARS-CoV-2 infection significantly alter the function of platelets, making them “hyperactive” and more prone to forming dangerous and potentially deadly blood clots. In turn, these clots contribute to the onset of heart attacks, strokes, and other serious complications in some patients who have the disease.

The findings, published in the journal Blood, came from studying 41 hospitalized COVID-19 patients. Seventeen patients were in the intensive care unit (ICU), including nine who were on ventilators. Researchers compared the blood from these patients to samples collected from healthy individuals who did not have the disease and who were matched for age and sex.

By analyzing the patient’s genes, researchers found that the novel coronavirus that causes COVID-19 triggers genetic changes in platelets. In laboratory studies, researchers studied platelet aggregation, an important component of blood clot formation, and observed that this phenomenon occurred more readily in COVID-19 patients. These changes, researchers noted, also altered how platelets interacted with the immune system, possibly contributing to inflammation of the respiratory tract and severe lung injury. The study was partly funded by NHLBI.