SARS-CoV-2 Vaccination and Immune Thrombocytopenia inChildren: A Multicenter Study

Background: Immune thrombocytopenia (ITP) is the most common acquired bleeding disorder in childhood. Although viral infections and some vaccinations are recognized triggers, data on the onset or exacerbation of ITP following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination in pediatric patients remain limited. Objectives: To evaluate the incidence and clinical characteristics of new-onset ITP and the safety of SARS-CoV-2 vaccination in children with preexisting or resolved ITP. Methods: We evaluated the incidence and clinical characteristics of ITP occurring after SARS-CoV-2 vaccination, as well as the effects of vaccination in children with preexisting ITP. Results: De novo ITP: five cases of new-onset ITP were identified nationwide, most of which occurred after the first vaccine dose (80%). Despite low median platelet counts at presentation, no major or fatal bleeding events were observed. Most patients responded favorably to first-line treatments (intravenous immunoglobulins and/or corticosteroids), and 80% achieved normal platelet counts at the last follow-up. Preexisting ITP: among 164 vaccinated patients with complete clinical data, only 8.5% (n = 14) experienced a transient platelet count decline or new bleeding manifestations. Notably, no relapses occurred among the 34 patients who were in clinical remission at the time of vaccination. Conclusions: ITP following SARS-CoV-2 vaccination in the pediatric population is exceedingly rare and generally mild. Moreover, SARS-CoV-2 vaccination appears safe in children with preexisting or resolved ITP.