PB0076 - Platelet activation and cytokine release of interleukin-8 and IP-10 after ChAdOx1 nCoV-19 coronavirus vaccine injection

Background: Coronavirus disease 2019 (COVID-19) vaccines are associated with serious thromboembolic or thrombocytopenic events, including vaccine-induced immune thrombocytopenia and thrombosis and immune thrombocytopenia, particularly AZD1222/ChAdOx1. According to the suspected mechanism, COVID-19 vaccines play an essential role in inflammation and platelet activation.

Aims: In this study, we analyzed the role of AZD1222/ChAdOx1 vaccines in platelet activation and the release of anti-PF4 antibodies and inflammatory cytokines in a cohort of healthy donors without VITT.

Methods: In this study, 48 healthy volunteers were enrolled. Blood samples were collected from peripheral blood over three-time points: before vaccination and 1 and 7 days after vaccination. The complete blood count, the levels of D-dimers, antiplatelet factor IV antibody, platelet surface markers of resting and activated platelets, platelet–leukocyte aggregations, and cytokine proteins were analyzed.

Results: Compared with pre-vaccination data, a decrease in leukocyte and platelet counts was observed 1 day after vaccination, which then recovered 7 days after injection. Only two healthy volunteers had increased anti-PF4 antibody levels; however, no thrombotic or bleeding events were observed in these two individuals. The percentage of PAC-1 under high ADP or thrombin receptor-activating peptide stimulation increased 1 day after vaccination. The percentage of neutrophil–platelet, and monocyte–platelet aggregations increased 7 days after injection. Interleukin-8 (IL-8) and interferon-gamma-induced protein 10 (IP-10) increased significantly.

Conclusion(s): Platelet activation and inflammation with the release of cytokines were observed after vaccination; however, no individuals had VITT. Mild thrombocytopenia with platelet activation and inflammation with an elevation of IL-8 and IP-10 were observed after AZ vaccination.