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 throm-bocytopenia. Many viruses and some vaccines have been identified as triggering the auto -immune 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.