Intracranial Hemorrhage After Pfizer-BioNTech (BNT162b2) mRNA COVID-19 Vaccination: A Case Report

The Coronavirus 2019 (COVID-19) pandemic has affected over 700 million people worldwide and caused nearly 7 million deaths. Vaccines currently developed or in development are the most effective tools for curbing the pandemic and mitigating its impacts. In Turkey, inoculation with the Pfizer-BioNTech COVID-19 vaccine (BNT162b2, also known as tozinameran) has been approved. We report a 56-year-old female patient with underlying essential hypertension who experienced intracranial hemorrhage after receiving her first dose of tozinameran. The patient underwent immediate surgical evacuation of the hematoma, during which a left middle cerebral artery bifurcation aneurysm was macroscopically identified and clipped. The patient was pronounced deceased on the second postoperative day. This is the second case of intracranial hemorrhage following tozinameran administration caused by a ruptured middle cerebral artery bifurcation aneurysm. Upon analyzing the case, there might be a connection between the vaccine's potential immune-triggering effect on hemodynamic patterns and the rupture of the previously unknown cerebral aneurysm. However, these severe complications do not justify avoiding vaccines; further studies are needed. This study emphasizes the need for increased vigilance in patients with underlying systemic comorbidities who have recently been vaccinated and to share our insights into the potential relationship between tozinameran and intracranial hemorrhage.