With each passing day we learn more about SARS-CoV-2 and what it does to our cells and our bodies. It seems, according at least to anecdotal reports, that infection with SARS-CoV-2 can induce serious blood clots in COVID-19 patients, as well as those who are otherwise asymptomatic. Abnormal clotting has been reported in COVID-19 patients in China, the United Kingdom, Italy, and United States.The resulting heart attacks, strokes, and pulmonary clots can be fatal.

From what we understand today, the blood clots appear to form in major vessels and migrate. Some are serious enough to require limb amputation. A recent paper in the New England Journal of Medicine reports 44 0f 216 COVID-9 patients had abnormalities in clotting time as measured by activated partial-thromboplastin time (aPTT). That’s 20% of those studied.

Further investigation was done in 35 patients who had tested positive for aPTT. The patients ranged in age from 18-83, 24 male and 6 female. Lupus anticoagulant assays were performed in 34 patients. Of those tested, 91% (31 patients) tested positive. This factor is elevated in less than ten percent of matched historical controls.

Despite its name, lupus anticoagulant is associated with increased blood clotting disorders. Lupus anticoagulant is an immunoglobulin that binds to a cell’s surface proteins and phospholipids. It is thought to act by binding to and aggregating platelets.

A possible explanation for the elevated levels, not offered by the authors, is that antibodies related to SARS-CoV-2 itself, or to infected cells or cell debris, triggers an autoimmune reaction similar to that found in lupus patients. Other researchers have recently reported favorable outcomes in patients treated with anticoagulants.

Management of COVID-19 patients will improve as physicians accumulate experience with the full range of symptoms associated with SARS-CoV-2 infections. On Wednesday, a team out of Mount Sinai in New York reported better results for hospitalized COVID-19 patients who received anticoagulant drugs. Their findings aren’t definitive, but they do add evidence to the potential importance using blood thinners to reduce the potential for life-threatening blood clots for COVID-19 patients.

This piece originally appeared on Forbes.