F2 and COVID-19: Increased EXTEM-CT is in line with previous studies where prolongation of prothrombin time with similar activation proteins as in EXTEM was identified in COVID-19 patients.28, 29In our in vitro analysis results, no impact on EXTEM-CT was observed with increasing LMWH doses, supporting the hypothesis that prolonged initiation of coagulation in COVID-19 may be due to viral effects and inflammatory activation.