COVID-19 vaccination in patients with hemophilia: Experience from a single center

Background: Coronavirus disease-2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV- 2), has resulted in an ongoing world-wide pandemic. Vaccination is the key countermeasure of the COVID-19 pandemic. Data on the efficacy, safety and immunogenicity of COVID-19 vaccination in patients with hemophilia -and in particular in those with HIV -are still scarce. Aim(s): The aim of our study was to characterize the immunogenicity and biomarkers of coagulation and endothelial perturbation after mRNA-COVID- 19 vaccination in HIV-positive hemophilic patients. Method(s): We collected blood from 24 adult HIV-positive hemophilic patients followed at our centre (19 with hemophilia A, 5 with hemophilia B) before and two weeks after the administration of the complete vaccination schedule with mRNA-1273 (Moderna Biotech). Most patients had severe hemophilia (n = 21). We measured antibodies to SARS-CoV- 2 spike protein by Elecsys (Roche) to assess immunogenicity and we evaluated protein C, VWF, D-dimer plasma levels as biomarkers of coagulation and endothelial perturbation. Anti-Platelet Factor 4 (PF4) antibodies were also measured. Result(s): Before vaccination, three patients out of 24 showed anti-Spike IgG levels >0.8 U/ml (cut-off value). Two weeks after completing the vaccination schedule, all patients had high values of anti-Spike IgG (min-max 2,387-12,500 U/ml). Mean (standard deviation) basal values of protein C, VWF and D-dimer (106 +/- 21%, 171 +/- 45%, 593 +/- 692 ng/ml respectively) were not significantly different from values measured two weeks after the second dose of vaccine (103 +/- 20%, 162 +/- 43%, 583 +/- 531 ng/ml). Anti-PF4 antibodies were detected in three patients with no associated clinical manifestations. None of the patients reported bleeding in the site of inoculation nor serious adverse events after the vaccination. Conclusion(s): Since immune abnormalities can occur in HIV-positive patients, it is important to collect data on COVID-19 vaccination immunogenicity. We demonstrated that hemophilic HIV-positive patients have a normal antibody response against SARS-CoV- 2 spike protein. In addition, mRNA-1273 had no effect on coagulation and endothelial perturbation.

Evaluation of D-dimer concentrations measured with three methods in patients with COVID-19

Background: COVID-19 is associated with an increased risk of venous thrombosis, even when patients are on standard-dose antithrombotic prophylaxis. Hence, the identification of biomarkers of thrombosis helps tailoring dosage of antithrombotic prophylaxis. D-dimer has been extensively employed as a biomarker and cut-off values at hospital admission have been proposed to stratify the risk of thrombosis and make decision on prophylaxis. However, D-dimer measurement is not standardized, and it is unknown if the cut-off values used for decision making can be used interchangeably between methods. Aim(s): To assess for concordance of results obtained with different commercially available laboratory methods measuring D-dimer. Method(s): Plasma samples collected from COVID-19 patients at the Hospital of Cremona were evaluated for D-dimer with three widely used immunoturbidimetric methods (Liatest D-di, Stago, Asnieres, France;D-dimer HS 500, Werfen, Orangeburg, NY;Innovance D-dimer, Siemens, Marburg, Germany). Result(s): A total of 87 COVID-19 patients [54 male and 33 female, median age of 73 years (range 28-98)] were enrolled in the study. No significant differences were found between mean D-dimer concentrations obtained with the three methods even when stratifying D-dimer levels in 4 groups (<1000, 1000-2000, 2000-5000, >5000 ng/mL) (Figure 1). The three methods showed substantial result agreement [Stago-vs- Werfen and Siemens-vs- Stago (Cohen's kappa coefficient of 0.760 and 0.699, respectively)] to an almost perfect agreement [Siemens-vs- Werfen (Cohen's kappa coefficient of 0.811)], with a p-value < 0.001. Results from the three methods showed a good linear correlation (Rho = 0.94) (Figure 2). Conclusion(s): The relatively good concordance of D-dimer results among the three investigated methods indicates that D-dimer cut-off values could be used interchangeably regardless of the method used for testing. The results pave the way to clinical trials aimed to assess the value of D-dimer as a biomarker to make decision on the intensity of antithrombotic prophylaxis in COVID-19 patients. (Figure Presented).

Anticoagulant response to tailored low molecular weight heparin regimens in patients with COVID-19 infection

Background : Covid-19 infection is associated with a widespread global activation of coagulation and affected patients are at an increased risk of thrombosis. Aims : Heparin therapy is effective in various setting in preventing thromboembolic complications and aim of this study was to assess heparin response in COVID-19 patients through anti-FXa test. Methods : In 52 patients, M:F ratio 59:41, median age 59 years old, admitted in different intensity of care units of our hospital, treated with different regimens of heparin (100 U/kg every 24 h in low intensity care, 70 U/kg every 12 h in intermediate intensity care and 100 U/kg every 12 h in intensive care unit), anti-FXa levels were measured immediately before and 3 h after subcutaneous enoxaparin administration. On the same samples thrombin generation tests were performed. Results : Patients treated with 100 U/kg every 24 h and 70 U/ kg every 12 h had median anti-FXa basal levels in the prophylactic range, respectively 0.18 and 0.22 U/ml, while patients treated with 100 U/kg every 12 h were in the anticoagulant range (0.37 U/ ml). Despite heparin therapy thrombin generation was elevated in COVID-19 patients, indicating a high level of coagulation activation. Conclusions : In conclusion we demonstrated that the biological response to enoxaparin in COVID-19 patients is in the expected range using anti-FXa assay and patients are not resistant to heparin therapy.