Abstract
An 84 year old male with a previous history of immune thrombotic thrombocytopenic purpura (iTTP) received the first dose of COVID19 mRNA vaccine (Pfizer-Biontech). Seven days later he was diagnosed with iTTP relapse. He received in-patient treatment with therapeutic plasma exchange, high dose steroids and rituximab and subsequently recovered. This case report highlights the need to monitor patients with iTTP following vaccination.