The Scientist: As you started performing these autopsies, what was most striking in terms of damage done to the body?

Sigurd Lax: Both lungs were symmetrically damaged, with damage to the alveoli, the tiny air sacs of the lungs. The pleurae, the double-lined membranes, surrounding the lungs showed very little inflammatory changes, a little fluid. Most cases had a strongly dilated heart, but the abdomen was not really involved. That was what we saw at first view.

TS: In your paper, you write that patients had blood clots in their small to mid-sized pulmonary arteries. What’s the significance of this finding?

SL: We saw an occlusion of multiple pulmonary arteries, usually in the periphery. There were some clots in the larger branches, but we think seeing more of them in the periphery means the clots are thrombotic rather than embolic. [Editor’s note: thrombotic clots develop in a blood vessel where there is damage, in this case in the lungs, while embolic clots form elsewhere, in a blood vessel in the leg, for example, and travel through body and become lodged in blood vessels of the lung.] And this concurs also with findings in pediatric cases, where you have occlusion of arteries in the fingers, for example, or necrosis in back, so in the skin on their back. So it’s not the pulmonary embolism which is the major cause of severe illness but the inflammation of the blood vessels and a change in the clotting system of the blood. And this causes occlusion of the pulmonary arteries, which increases the pressure of pulmonary circulation and then leads to an insufficiency of the heart to pump blood through the body properly.