• bleeding disorders & coagulopathies
• public health
• infection control

The rapid pace of COVID-19 vaccine development and the uncertainty of potential adverse effects have led to concerns about safety and some hesitancy in vaccine uptake. In the UK, four COVID-19 vaccines —ChAdOx1-S (Oxford–AstraZeneca, hereafter ChAdOx1), mRNA BNT162b2 (Pfizer–BioNTech), mRNA-1273 (Moderna) and Janssen—have been authorised for use in the national vaccination programme. Reports of extremely rare adverse events of concurrent thrombosis and thrombocytopenia following vaccination with ChAdOx1 have been well documented and have led to several countries suspending or restricting its use.1 To address ongoing public, professional and regulatory concerns, evidence on the safety of COVID-19 vaccines relating to potential haematological adverse events is required, especially given the relative paucity of population-based data. Here we present two cases of acute immune thrombocytopenia purpura (ITP) following administration of ChAdOx1 treated in our department.

Patient 1 was an 86-year-old man presenting with gingival bleeding, tongue blisters and widespread ecchymoses 2 days after receiving one dose of ChAdOx1. He had no personal or family history of bleeding disorders. Initial blood showed a profound thrombocytopenia with a platelet count of 4×10⁹/L. Haemoglobin (Hb) concentration, white cell count (WCC) and coagulation studies were within normal range. Peripheral blood film was normal apart from severe thrombocytopenia. Autoimmune, viral serology and haematinics were unremarkable. He was commenced on treatment for ITP with high-dose dexamethasone 20 mg for 4 days. A CT of the head …