These biphasic waveforms occur frequently in critically ill patients on the ICU and are caused by the formation of a precipitate of CRP and very-low-density lipoprotein after the recalcification of plasma.47In COVID-19, high CRP concentrations and disseminated intravascular coagulation may cause these biphasic waveforms in optical aPTT analyzers. Here, CRP is linked to Disseminated intravascular coagulation.