Introduction
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel virus first detected in Wuhan in December 2019. Few months later, the World Health Organization (WHO) declared a worldwide pandemic. This virus may cause severe viral pneumonia with acute respiratory distress syndrome causing millions of deaths.1,2 Currently, there is no effective treatment for coronavirus disease 2019 (COVID-19).3 However, several vaccines have been developed worldwide to reduce COVID-19 mortality and morbidity.4 Those vaccines have obtained emergency use approval by the WHO in several countries increasing the risk of vaccine safety issues and some adverse events have been reported.5–7 Most frequent were injection site reactions or systemic effects (eg, fatigue, headache, body pain, fever), with rare serious adverse events (eg, anaphylaxis, Guillain-Barré, thrombosis with thrombocytopenia Syndrome).8–10 Several cases of Thrombotic Thrombocytopenic Purpura (TTP) induced by COVID-19 vaccination have been reported in the literature.11–14 TTP is a rare hematologic disorder classically characterized by the pentad of fever, hemolytic anemia, thrombocytopenia, renal failure, and neurologic dysfunction. However, most patients do not have the entire pentad.15 This disease is caused by a severe decrease in the activity of the von Willebrand factor-cleaving protease ADAMTS-13 which can be either congenital or acquired due to anti-ADAMTS-13 autoantibodies.11 Various events may initiate the production of those antibodies such viral infections, medication, pregnancy, malignancies and occasionally vaccinations.16 Here, we report two cases of acquired TTP after two inactivated COVID-19 vaccines: BBIBP-CorV vaccine known as the Sinopharm COVID-19 vaccine and CoronaVac known as the Sinovac vaccine. To the best of our knowledge, the present cases are the first reported cases of acquired TTP after inactivated virus COVID-19 vaccines.