These authors observed that, in a high percentage of their investigated patients, “HIT occurred not only in patients with heparin exposure, such as CRRT” (Continuous renal replacement therapy) “but also in heparin-naïve patients, suggesting that spontaneous HIT may occur in COVID-19.” They came to a conclusion that “Anti-heparin-PF4 antibodies are induced in critical COVID-19 patients, resulting in a progressive platelet decrease. Here, PF4 is linked to COVID-19.