Author(s): Krzywicka, Katarzyna ; van de Munckhof, Anita ; Zimmermann, Julian ; Bode, Felix J. ; Frisullo, Giovanni ; Karapanayiotides, Theodoros ; Pötzsch, Bernd ; Sánchez van Kammen, Mayte ; Heldner, Mirjam R. ; Arnold, Marcel ; Kremer Hovinga, Johanna A. ; Ferro, José ; de Sousa, Diana Aguiar ; Coutinho, Jonathan M.
Date: 2022
Persistent ID: http://hdl.handle.net/10451/52654
Origin: Repositório da Universidade de Lisboa
Cerebral venous thrombosis (CVT) is the most common and severe manifestation of vaccine-induced immune thrombotic thrombocytopenia (VITT), which is a rare side effect of the SARS-CoV-2 vaccine ChAdOx1 nCoV-19 (Vaxzevria, AstraZeneca/Oxford). The absolute risk of VITT and VITT-related CVT is estimated at 20 and 8 per million first doses of ChAdOx1 nCoV-19, respectively. So far, no definite VITT cases occurring after a second ChAdOx1 nCoV-19 vaccine dose have been reported, raising the question of whether VITT only occurs after a first dose. Two pharmacovigilance studies reported cases of thrombosis with thrombocytopenia after a second ChAdOx1 nCoV-19 dose, but because of lack of clinical data, none of these could be classified as VITT. Knowledge on whether VITT can occur after a second ChAdOx1 nCoV-19 dose is relevant for clinicians and policymakers, especially in low- and middle-income countries, which are currently the main users of adenovirus-based vaccines. We used data from the “CVT after SARS-CoV-2 vaccination” registry to identify VITT-related CVT cases occurring after a second ChAdOx1 nCoV-19 dose. Details of this registry have been published. Briefly, this ongoing study collects data on patients with CVT with symptom onset ≤28 days from SARS-CoV-2 vaccination, regardless of the type and dose of vaccine. The study is endorsed by the European Academy of Neurology and the European Stroke Organization. Investigators are instructed to report consecutive cases from their hospitals. The ethical review board of the Academic Medical Centre issued a waiver of formal approval for this observational study. Each center obtained local permission to carry out the study and acquired informed consent for the use of pseudonymized care data according to national law. We used the case definition criteria of the United Kingdom expert hematology panel to classify cases as definite, probable, possible, or unlikely VITT after ChAdOx1 nCoV-19 administration among CVT cases reported until 1 December 2021.
