Abstract
While the number of people who have been vaccinated against coronavirus disease 2019 (COVID-19) in Portugal keeps rising, the risk of complications, although rare, keeps rising too. We report a case of vaccine-induced thrombotic thrombocytopenia (VITT) in a 30-year-old previously healthy male after vaccination with Ad26.COV2.S. The patient presented to the emergency department (ED) with abdominal pain and headache. Laboratory tests revealed thrombocytopenia, high D-dimer levels, and fibrinogen consumption. Thoracoabdominal CT scan showed a thrombus in the portal mesenteric venous axis. A positive PF4 heparin enzyme-linked immunosorbent assay confirmed the VITT diagnosis, and the patient was started on intravenous immunoglobulin. Both clinical complaints and laboratory findings resolved within six days, and he was discharged to follow-up. This case shows that general symptoms after vaccination should not be depreciated, highlights the importance of early diagnosis and treatment, and raises new questions about the follow-up and further study of these patients.