Background/Objectives: Through the past several years, a constant interaction has been implicated between complement and coagulation cascades. SARS-CoV-2 infection and bacterial sepsis are potent activators of both cascades. This study aims to compare the extent of complement and intrinsic coagulation pathway activation (and the interplay between them) among patients with COVID-19 and bacterial sepsis. Methods: Serum and plasma samples were collected from 25 ICU patients (11 patients with COVID-19 and 14 patients with bacterial sepsis) at two time points (on admission and either on improvement or deterioration). The activities of coagulation factors XI and XII and complement factors C3a and C5a were measured at both time points. Results: The activities of factors XI and XII were increased in both groups of patients and at both time points. However, there were no statistically significant differences between SARS-CoV-2 and bacterial sepsis patients. On the other hand, both C3a and C5a were significantly higher in the COVID-19 group on admission. This correlation was preserved on reassessment. Conclusions: Complement activation seems to be more enhanced in COVID-19 than bacterial sepsis. However, the lack of statistical significance in factors XI and XII indicates t the presence of additional pathways for complement activation in SARS-CoV-2 infection.

Background/Objectives: Acutely ill patients in hospital are at high risk for thrombosis, even post-discharge. However, the safest and most effective strategy for thromboprophylaxis in such patients is still under debate. Our aim was to compare the subcutaneous use of low-dose prophylactic enoxaparin versus intermediate-dose tinzaparin. Methods: Patients in an internal medicine clinic of a tertiary hospital in Athens, Greece, with increased risk for thrombosis (PADUA score ≥ 4) received either intermediate-dose tinzaparin (8000 anti-Xa units) or 40 mg enoxaparin as thromboprophylaxis. Efficacy and adverse effects were evaluated and compared up to 14 days post-discharge. Results: A total of 251 patients who received tinzaparin were compared with 95 patients under enoxaparin thromboprophylaxis. No statistically significant difference was found in the number of bleeding and/or clinically evident thrombotic events between the two groups [6 versus 14 bleeding (p = 0.2603) events and 0 versus 1 venous thrombotic event (p = 0.999) in the enoxaparin and tinzaparin groups, respectively]. Moreover, no difference was found in length of stay [enoxaparin: 10 days (95%CI: 9–12 days); tinzaparin: 8 days (95%CI: 8–10 days, HR = 1.18, 95%CI: 0.91–1.54, p = 0.2] or mortality [11 deaths with enoxaparin (11.58%, 95%CI: 6.59–19.55%) and 50 deaths with tinzaparin (19.92%, 95%CI: 15.45–25.30%, OR: 1.9, 95%CI: 0.94–3.83, p = 0.069)]. The use of thromboprophylaxis for two weeks post-discharge did not result in any bleeding or clinically evident thrombotic events in either group. Conclusions: In our cohort, the use of intermediate-dose tinzaparin was similar to the use of low-dose enoxaparin for patients with a high PADUA score in terms of thrombotic and/or bleeding events.