Background and Objectives: Post-COVID-19 condition is thought to affect 10– 20% of people at least 3 months after a diagnosis of COVID-19 and two months of symptoms. Post-COVID-19 condition presents itself with many clinical effects with varying degrees of severity ranging from a mild cough to a life-threatening coagulopathy. Our study aimed to identify a relationship between the titers of anti-SARS-CoV-2 IgG and anticoagulation parameters: antithrombin III (ATIII), protein C (PC) and thrombomodulin (TM).
Materials and Methods: Blood plasma was collected from healthy donors aged 25– 45 who had recovered from COVID-19 3– 6 months ago and their titers of anti-SARS-CoV-2 IgG and ATIII, PC, and TM were measured.
Results: We found that concentrations and activities of key anticoagulation parameters (ATIII, PC, and TM) measured in donor plasma during the post-COVID-19 varied in relation to the titers of anti-SARS-CoV-2 IgG.
Conclusion: While we identified a dysfunction of anticoagulation parameters in patients with post-COVID-19, we aim to explore the subpopulation antibody IgG fraction directly using in vivo and in vitro experiments with the possibility to contribute to the development of treatment options for post-COVID-19 conditions.

Keywords: long-COVID, antithrombin III, thrombomodulin, protein C