Beyond elevated levels of PF4 and HMGB1, patients suffering from severe COVID-19 display elevated markers of platelet activation including thromboxane A2 (Hottz et al., 2020; Zhang et al., 2020), surface expressed P-selectin (CD62P) and CD63 (Hottz et al., 2020; Manne et al., 2020; Nicolai et al., 2020; Taus et al., 2020; Zhang et al., 2020), activated glycoprotein (GP) IIb/IIIa (Bongiovanni et al., 2021; Léopold et al., 2021), as compared to healthy controls or to patients suffering from other pulmonary infections. The gene discussed is PF4; the disease is COVID-19.