VITT and Second Doses of Covid-19 Vaccine

Autoimmune post-COVID vaccine syndromes: does the spectrum of autoimmune/inflammatory syndrome expand?

“…One aspect of the discussion is whether to continue the application of subsequent vaccinations for patients who develop autoimmune manifestations after the first dose of the vaccine. A recent study suggests that in some cases, such as VITT, administering a second dose, regardless of the vaccine received against COVID-19, did not cause any adverse events [ 39 ]. The absence of relapse after the second dose suggests that, in some cases, the autoimmune syndrome is not related to components of the vaccine such as spike protein.…”

Persistence of Platelets Activation Prior to Second Doses of Covid-19 Vaccine After Vaccine-Induced Immune Thrombotic Thrombocytopenia

“…None of the 40 cases who received a second dose has developed complication regardless of the vaccine received. 1 However, it is unclear if these patients were anticoagulated at that time or if platelet-activation assays remained positive prior to vaccination. Most of VITT cases shows normalization of platelet activation after 12 weeks.…”

Pathogenesis of vaccine-induced immune thrombotic thrombocytopenia (VITT)

“…In adverse immune reactions against drugs, recurrence of symptoms during re-exposure of the suspected compound is often considered proof of causality. In this regard, the observation that 34 VITT patients of the German cohort and 40 VITT patients of the UK cohort received their second vaccination shot with mRNA vaccines without signs of thrombosis or decreasing platelet counts is relevant [34] , [35] , [36] . This observation is strong in vivo evidence that the mRNA vaccines do not contain or induce cofactor(s) required for anti-PF4 antibody-mediated prothrombotic activation of platelets; especially as in the German cohort, several patients still had circulating platelet-activating anti-PF4 antibodies in their plasma at the time of the second shot mRNA vaccination.…”

“…This observation is strong in vivo evidence that the mRNA vaccines do not contain or induce cofactor(s) required for anti-PF4 antibody-mediated prothrombotic activation of platelets; especially as in the German cohort, several patients still had circulating platelet-activating anti-PF4 antibodies in their plasma at the time of the second shot mRNA vaccination. However, Lacy et al 2021 [36] recently described five patients (one with confirmed and four with possible VITT) who received a second vaccination dose with ChAdOx1 nCoV-19. These patients showed no relapse of VITT or any adverse reaction.…”