Quick drop of platelet counts in children with chronic immune thrombocytopenia after COVID-19 mRNA vaccination: case reports.

Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by isolated thrombocytopenia. Many viruses and some vaccines have been identified as triggering the autoimmune process, including parvovirus, human immunodeficiency virus, Epstein-Barr virus, rubella, and measles. However, ITP in association with coronavirus disease 2019 (COVID-19) vaccination has not been reported so far. We describe the cases of two young girls affected by ITP presenting a quick reduction of platelet count after receiving Pfizer-BioNTech COVID-19 vaccine.