Platelet derived microparticles [42] and high levels of angiopoietin-2, follistatin and PAI-1, markers of endothelial injury, increase the risk of mortality [43], and signs of intussusceptive angiogenesis, a proposed mechanism for vessel generation in late stages of chronic lung injury, have been found in lung biopsies of COVID-19 patients [44]. Here, FST is linked to injury.