Infection with COVID-19 has been associated with thrombosis, or blood clots, involving the veins and arteries. The risk of blood clots is highest for individuals admitted to hospital with COVID-19 infection, occurring in about 5% of people admitted to a regular hospital ward and up to 20% for those in the intensive care unit (ICU), on life-support. The risk of blood clots for individuals with COVID-19 but not requiring admission to hospital is lower at about 1% [1]. While highly uncommon, vaccination with adenovirus-based vaccines is also associated with blood clots through a condition called vaccine-induced thrombotic thrombocytopenia (VITT). To better understand the key coagulation risks and considerations around COVID19 vaccination and patient management, Roche Diagnostics Asia Pacific recently spoke with Dr. Ng Heng Joo, Senior Consultant & Head of Department of Haematology at Singapore General Hospital.