The virus inflames the blood vessels, which makes diffusion of gases between the lungs and the bloodstream more difficult. This leads to hypoxia. The hypoxic cascade it causes leads to hemes detaching, becoming free hemes, which has to bind to nitric oxide. As time goes on, nitric oxide gets depleted, and you end up with pulmonary embolism or clotting, which is a natural consequence of low NO. If people went to the hospital at the first sign of stroke, and received NO treatment, this would be avoidable. The young people who died in NYC ignored stroke symptoms for a day or more on average, so while education is important, it is treatable if caught.