Anti‐severe acute respiratory syndrome coronavirus‐2 adenoviral‐vector vaccines trigger subclinical antiplatelet autoimmunity and increase of soluble platelet activation markers

Abstract

severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative agent of the coronavirus disease 2019 (COVID-19) pandemic, has led to >5.7 million deaths worldwide, and an unprecedented global societal and economic disruptive effect. 1,2 To slow down the COVID-19 pandemic an unequalled

Long‐term effects of Pfizer‐BioNTech COVID‐19 vaccinations on platelets

“…These results indicate that the vaccinations did not have long‐term effects on platelet activity. Short‐term transient effects occurring 1–2 months after the vaccination were presumably due to the vaccination‐induced elevations of soluble platelet activation markers such as soluble P‐selectin [ 11 , 12 ], which may lead to the increase in concentrations of platelet aggregates. The fluctuations in the concentrations of platelet‐leukocyte aggregates in Figure 2E can be attributed to the immediate immune response after the vaccination, the variation of the physical conditions of each subject, and the subject‐to‐subject differences.…”

From Immunogen to COVID-19 vaccines: Prospects for the post-pandemic era

“…Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a prothrombotic syndrome identified after the inoculation of adenoviral vector-based vaccines, characterized by thrombocytopenia, systemic activation of coagulation, extensive venous (especially cerebral venous) thrombosis and platelet factor 4(PF4) antibody [179] . Abbattista et al calculated the incidence of adverse events correlated with VITT of four vaccines candidates (including BNT162b2, mRNA1273, AZD1222 and Ad26.…”

“…COV2. S [179] , [181] . PF4 antibody can be bound to specific site on PF4, corresponding to heparin, forming immune complex and activating platelets through Fcγ-Receptor Iia [182] .…”

“…Furthermore, the vaccine-elicited anti-Spike-specific antibody (Ab1) has an immunogenic amino acid sequence, and it is termed an idiotype, which elicits an anti-idiotype antibody (Ab2) antibody response. Ab2 antibodies can be bound to antibodies that protectively neutralize Ab1 and impair Ab1 efficacy [179] .…”

Vaccine-induced immune thrombotic thrombocytopenia

“…Additionally, studies suggest that the intravenous administration of vaccine components may promote the formation of platelet-vaccine component complexes and increase their deposition in the splenic marginal zone [ 31 , 32 ]. Subsequently, this may drive B-cell development and the production of antibodies to PF4 and other platelet antigens (such as platelet surface integrins) [ 33 ]. Adenoviral vector-based vaccines have also been shown to bind to PF4 in vitro [ 34 ], which may increase adenoviral vector binding to the platelet surface via PF4 interactions and could help to explain the relatively higher occurrence of VITT associated with adenoviral vector-based vaccination.…”