Moreover, in the acute COVID-19 patients, the effect of the neutralization of TFPI activity accounted for an increase of 3.9 ± 2.8 pM/mL in FXa production (+39%), which was lower compared to that measured in the HSs (7.1 ± 2.2 pM/mL FXa, +63%). Here, TFPI is linked to COVID-19.