Changes in the hemostatic system as a result of SARS-CoV-2 infection and/or vaccination often have a number of adverse consequences and are an urgent problem.
OBJECTIVE
To study the parameters of plasmic hemostasis by thrombodynamics in individuals revaccinated against the SARS-CoV-2 virus by domestic vaccines, namely by the combined vector vaccine for prevention of coronavirus infection caused by the SARS-CoV-2 virus (Gam-COVID-Vac) and the coronavirus inactivated whole-virion concentrated purified vaccine (CoviVac), including in their combination.
MATERIAL AND METHODS
The study was carried out within the framework of the SATURN prospective register («Comparative evaluation of reactogenicity and potency of heterological vaccination against COVID-19 schemes»), which included individuals who received revaccination against the SARS-CoV-2 virus (homologous and heterological schemes) based on a combination of two vaccines: Gam-COVID-Vac and CoviVac. A number of subjects equal 200 participated in the study, which, depending on the chosen scheme, were divided into three groups. Group I included the study participants (n=106), who underwent revaccination according to the homologous scheme with the Gam-COVID-Vac preparation, in group II the participants of the study (n=54) had revaccination according to the heterological scheme with Gam-COVID-Vac and CoviVac preparations, in group III the subjects (n=40), were revaccinated according to the homologous scheme with the CoviVac drug.
RESULTS
Changes in the parameters of thrombodynamics compared to the initial level have been found in the dynamics 6 and 12 months after the revaccination in the individuals of each group. The main ones were connected with the speed indicators V and Vst. An increase in favor of hypercoagulation was recorded for subjects in groups I and III during the 5th visit: 30.90 [28.30; 37.22] µm/min and 30.45 [28.20; 34.28] µm/min, respectively, for V and 30.20 [28.30; 34.60] µm/min and [30.30; 32.10] µm/min for Vst. Tlag, another key parameter of the test, increased in each group but did not go beyond the reference values. The incidence of spontaneous thrombosis detection (which is normally absent) in persons of group I exceeded the initial and final values (p5—3.6<0.001). The supportive indicators (Vi, D and CS) remained within the normal range under follow-up.
CONCLUSION
The use of homologous vaccination schemes showed an increase in the growth rate of the clot and a steady clot growth rate six months after the revaccination, indicating a hypercoagulable state. In addition, the increased risk of thrombotic event was confirmed by the presence of spontaneous clots in group I participants. Despite this, during the study none of the participants had clinically pronounced thromboembolic complications, and in the final control during the 6th visit the indicators V, Vst returned to the reference values. At this stage, it is not possible to establish a relationship of these changes with SARS-CoV-2 vaccines use.
