There may also be the heme component. But a quick glance at my roster of COVID ICU patients shows all of them with improved O2 saturation on 40% oxygen and high PEEP, when with high flow O2 via nonrebreather we couldn't get them above 88%. It's not a typical ARDS, but it's ARDS by definition (acute, noncardiac, low P:F ratio). We also have a patient who tested positive and has had transfusions for a gi bleed, and he hasn't improved much with fresh blood.