HEMOSTATIC ACTIVATION MARKERS AND SEROLOGICAL RESPONSE IN SUBJECTS RECEIVING ANTICOVID- 19 VACCINATION

ABSTRACT

Background: SARS-COV2 infection is associated with inflammation, hypercoagulability and endothelial damage. Anti-SARS-COV2 vaccines have radically changed the course of the pandemic, however, reports on rare thrombotic events raise concern in the scientific community and the general population. Aims: In a prospectively enrolled cohort of adult subjects undergoing mRNA or adenovirus vector vaccination, we wanted to longitudinally evaluate the changes in levels of hemostatic biomarkers (i.e. activation of blood coagulation and perturbance of endothelium and fibrinolysis), together with the serological response, and occurrence of manifest thrombotic complications. Methods: Peripheral venous blood samples were collected at enrollment (day 0, D0) before the 1st vaccine dose, and on 15 (D15), 60 (D60), 90 (D90) and 180 (D180) days after the 1st dose. At each time point, hemostatic markers (i.e., fibrinogen, D-dimer, FVIII, von Willebrand Factor [vWF] antigen and activity, F1+2, thrombomodulin, protein C, protein S, FXIII, tPA, and PAI-1), and anti-Spike receptor-binding-domain protein (anti-S/RBD) IgG were measured. Follow up is currently continuing. Results: Fifty-three subjects (57% males) with a median age of 50 years (range 23-86) were enrolled into the study and followed-up for 6 months 36 (68%) received BNT162b2, 6 (11%) mRNA-1273, and 8 (15%) ChAdOx1 nCoV-19 vaccines, in 2 doses over 21, 30 and 77 days, respectively;while 3 (6%) subjects received Ad26.COV2.S as single shot. Twenty individuals (38%) reported previous history of COVID-19, with a mean time from infection to vaccination of 10 months (4-18);only 1 required Hospitalization. Nine subjects presented cardiovascular risk factors and 4 a prior, non-active, cancer;3 were on anticoagulation for atrial fibrillation. The evaluation of the hemostatic biomarkers at the different time points showed variations in some of the parameters evaluated, with median values remaining within normal range levels. Specifically, compared to baseline, we observed a significant increase in thrombomodulin at D90 (p=0.001) and D180 (p=0.03), in parallel to a significant decrease in fibrinogen (D60), vWFAg (D60 and D180), FVIII (D60, D90 and D180), and TPA (D60 and D90) levels. The reduction of these biomarkers was particularly evident in individuals with a history of COVID-19. Of interest, this group of subjects was also characterized by significantly lower levels of PAI-1 both at baseline (7.18 ng/mL vs 17.53 ng/mL;p<0.0001), and at other time points (p<0.0001), and by an increase in F1+2 at D90 (p=0.02). The association between lower baseline PAI-1 levels with history of COVID-19 was confirmed by linear regression analysis (B= -10.351, p=0.013), and was independent by the time of infection resolution. Notably, no differences were observed in the hemostatic biomarkers according to vaccine types. All subjects positively responded to vaccination with a significant increase in anti-S/RBD IgG from baseline (D0) to each time point, especially COVID-19 subjects (D15, D60, and D90p<0.0001;D180p=0.031). No thrombotic or cardiovascular complications occurred during follow-up. Summary/Conclusion: No hypercoagulable state elicited by COVID-19 vaccination was observed, contrarily we detected an overall persistent reduction of coagulation activation over time. Subjects with previous SARS-COV2 infection had persistently low levels of PAI-1, supporting enhanced fibrinolysis activation. Compared with recent studies, our results provide a longer observation follow-up with all vaccine types and reassure on the safety of anti- SARS-COV2 vaccination.