Hemostatic characterization of post-covid-19 convalescent plasma donors: The bergamo experience

ABSTRACT

Background: Severe COVID-19 is associated with a profound derangement of the hemostatic system characterized by hypercoagulability, complement activation and endothelial cell perturbation. After disease resolution, some convalescent subjects still experience post-COVID-19 symptoms. No information is available on persistence of hemostatic alterations in this setting. Bergamo city, represents one of the first and most affected area by SARS-CoV-2 infection in the world. For this reason, since the beginning we were actively involved in hyperimmune plasma collection from COVID-19 convalescent subjects. Aims: In this study, in a large cohort of convalescent donors of hyperimmune plasma, we aimed to characterize select hemostatic parameters of hypercoagulability and endothelial cell perturbation and their association with disease severity, demographic characteristics, and antibody levels. Methods: Recovered COVID-19 patients eligible to plasma donation were tested for the SARS-CoV-2 antibodies by the anti-N IgG SARSCoV- 2 antibodies (Abbott Laboratories, IL, USA, Anti-N Abs), and/or the anti-S IgG SARS-CoV-2 antibodies (Liaison-Diasorin, Sallugia-VC, Italy, Anti-S Abs), according to the manufacturer's instructions. Fibrinogen, protein C, protein S, factor V, factor VIII, factor XIII, D-dimer, and von Willebrand factor (vWF) were assessed. Results: 425 subjects have been included (275M/150F) with a median age of 48 years (range 19-67 years). Among convalescent subjects admitted to the donation, male gender, age > 40 years, and previous hospitalization for COVID-19, were identified as independent predictive factors for significantly (p<0.001) higher levels of SARS-CoV-2 IgG (both anti-S and anti-N). Hemostatic parameters including fibrinogen, protein S, factor V, factor VIII, factor XIII, and D-dimer were not different between severe and non-severe COVID-19. Differently, convalescent subjects with previous severe COVID-19 showed significantly higher levels of vWF (124±40 vs 121±41 %, p<0.001) and PC (119±19 vs 109±19 %, p<0.001) compared with non-severe COVID-19 subjects. In addition, significant positive correlations were found between vWF levels and anti-S Abs (vWF antigen r=0.216;vWF activity r=0.257 and vWF RiCof r=0.226, p<0.01). Summary/Conclusion: Our data show that gender, age and severe disease can be potential predictors of an increased immunological response. Furthermore, convalescent subjects show a persistently high vWF levels, suggesting a persistence of the endothelial activation, despite of clinical disease remission.