Histological and immunohistochemical findings in a fatal case of thrombotic thrombocytopenia after ChAdOx1 nCov-19 vaccination.

This case report describes a fatal case of a young woman with superior sagittal, transverse and sigmoid sinus thrombosis after administration of the ChAdOx1 nCov-19 vaccination. Eleven days post-vaccination she was found unconscious and transferred to the Emergency Department. Blood parameters showed low platelets, and a CT scan showed an extensive left intracranial hemorrhage and the presence of an occlusive thrombus of the superior sagittal sinus. She under-went a craniectomy, but after the intervention, she remained in a comatose state. After a few days, her clinical conditions worsened, and she died. A complete autopsy was performed which showed a thrombosis of the cerebral venous district, of the upper and lower limbs. A blood sample was also performed to carry out a gene study about the predisposition to thrombosis. The organ samples were studied through light microscope both in hematoxylin-eosin and immunohistochemical examination, and showed a strong inflammatory response in all samples and at the site of thrombosis. Our study aims to provide a proper autopsy technique to study the entire cerebral venous system through a multidisciplinary approach (anatomical dissection and neurosurgery) in post-vaccine venous thrombosis.

COVID-19 Vaccine and Death: Causality Algorithm According to the WHO Eligibility Diagnosis.

The current challenge worldwide is the administration of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines. Even if rarely, severe vascular adverse reactions temporally related to vaccine administration have induced diffidence in the population at large. In particular, researchers worldwide are focusing on the so-called "thrombosis and thrombocytopenia after COVID-19 vaccination". This study aims to establish a practical workflow to define the relationship between adverse events following immunization (AEFI) and COVID-19 vaccination, following the basic framework of the World Health Organization (WHO). Post-mortem investigation plays a pivotal role to support this causality relationship when death occurs. To demonstrate the usefulness and feasibility of the proposed workflow, we applied it to two exemplificative cases of suspected AEFI following COVID-19 vaccination. Based on the proposed model, we took into consideration any possible causality relationship between COVID-19 vaccine administration and AEFI. This led us to conclude that vaccination with ChAdOx1 nCov-19 may cause the rare development of immune thrombocytopenia mediated by platelet-activating antibodies against platelet factor 4 (PF4), which clinically mimics heparin-induced autoimmune thrombocytopenia. We suggest the adoption of the proposed methodology in order to confirm or rule out a causal relationship between vaccination and the occurrence of AEFI.