[Severe thrombocytopenia after COVID-19 mRNA vaccination].

ABSTRACT

The Japanese Society of Hematology recently published on acute exacerbation of immune-mediated thrombocytopenia (ITP) after mRNA-based severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination. In addition, there is a growing concern for the development of the newly diagnosed ITP after SARS-CoV-2 vaccination. Herein, we report two cases of severe thrombocytopenia associated with bleeding tendencies at 4 and 14 days after BNT162b2 mRNA vaccination. Platelet counts returned to normal following platelet transfusion or treatment with intravenous immunoglobulin and dexamethasone. To our knowledge at the time of the draft of this manuscript, nine cases of SARS-CoV-2 vaccine-induced ITP have been reported. Although most patients showed favorable clinical courses similar to that of our cases, critical thrombocytopenia can lead to unfavorable outcomes. A national survey may be required to examine the causal relationship between SARS-CoV-2 vaccination and the emergence of the newly diagnosed ITP and clinical outcomes of vaccine-induced thrombocytopenia.