Vaccination against COVID-19 is the most recognised means of containing the pandemic. Vaccines are not without side effects, particularly vascular thrombosis. But before blaming the vaccines, a thorough assessment of thrombotic risk factors is necessary. We report a case of arterial and venous thrombosis after vaccination with AstraZeneca revealing an exaggeration of factor VIII in a 37-year-old female patient. The angioscanner showed a venous thrombosis of the right subclavian, a pulmonary embolism and the presence of a thrombus in the aorta. The biology was in favour of a high level of factor VIII. The patient was treated with an antivitamin K, and the clinical evolution was favourable.