These data show that TGF-β is a key mediator in the pathogenicity of COVID-19 and likely vital to the virus’s asymptomatic carriage that contributes to high viral loads and increased viral spread, delayed progression to severe illness, and transition in a subset of patients into a pro-inflammatory, pro-fibrotic final phase of illness with prominent microvascular clotting. The gene discussed is TGFB1; the disease is COVID-19.