Severe Immune Thrombocytopenia after COVID-19 Vaccination: Two Case Reports and a Literature Review.

We herein report two cases of coronavirus disease 2019 (COVID-19) vaccine-induced immune thrombocytopenia (ITP). A 69-year-old Japanese man developed severe thrombocytopenia after COVID-19 vaccination. He had oral bleeding and hemoptysis but no thrombotic symptoms. He improved rapidly with oral prednisolone therapy. A 34-year-old Japanese woman had generalized purpura after COVID-19 vaccination. Her platelet count improved rapidly after treatment with prednisolone and eltrombopag. The occurrence of two cases of ITP after COVID-19 vaccination at a single institution suggests that there could be more such undiagnosed cases, especially cases of mild secondary ITP.