VPB0314 - Relationship between recurrence of congenital and immune-mediated thrombotic thrombocytopenic purpura and mRNA-based COVID-19 vaccination: A questionnaire survey in a Japanese cohort

Background: Patients with thrombotic thrombocytopenic purpura (TTP) are theoretically at high risk for thrombosis due to COVID-19, which is attributed to the increase in plasma von Willebrand factor levels and decrease in plasma ADAMTS13 activity with disease severity of COVID-19. So far, one case of a flare of congenital TTP (cTTP) and some cases of de novo immune-mediated TTP (iTTP) have been reported following COVID-19 vaccination worldwide.

Aims: This study aimed to investigate whether mRNA-based COVID-19 vaccines could induce TTP episodes in patients with a history of TTP.

Methods: A questionnaire was administered to Japanese patients with cTTP and iTTP in October 2021 regarding the adverse events they experienced after receiving an mRNA-based COVID-19 vaccine. Only patients aged ≥ 12 years were included in the study. The questionnaire was sent to physicians in-charge of managing patients with TTP. This study was limited to analyzing the risk of TTP recurrence.

Results: A total of 42 patients with cTTP and 33 patients with iTTP were included in the study. Among the patients with cTTP, 38 were fully vaccinated (Table 1), and four were unvaccinated. No severe adverse effects of vaccination, especially recurrence of cTTP, were observed in all patients. Moreover, the platelet counts of the patients remained unchanged. Those receiving fresh frozen plasma infusion were vaccinated within two weeks of plasma infusion. Out of the 33 patients with iTTP, 26 were fully vaccinated (Table 2), and seven patients were unvaccinated. No recurrence was observed in patients with iTTP. Likewise, the platelet counts of the patients remained unchanged.

Conclusion(s): We believe that all patients with cTTP and iTTP should receive COVID-19 vaccination, given its benefits. Careful observation for any adverse events should be after vaccination.