biostudies-literatureUnknown7(8)Mendes-de-Almeida DP<h4>Background</h4>The emergence of new variants of SARS-CoV-2 has led to the administration of different booster vaccines to mitigate COVID-19. Vaccines with adenoviral vectors have been rarely associated with vaccine-induced immune thrombotic thrombocytopenia (VITT).<h4>Objectives</h4>This study aimed to describe 15 cases of VITT after the third and fourth doses of the COVID-19 vaccine in Brazil.<h4>Methods</h4>Cases were reported after all kinds of anti-SARS-CoV-2 booster vaccinations between October 17, 2021, and September 4, 2022.<h4>Results</h4>Of the 26 suspected cases, 15 cases of VITT were analyzed. Of these, 10 were classified as definite VITT, 2 as probable, 1 as possible, and 2 as unlikely. The estimated frequency of definite, probable, or possible VITT was 0.33 cases per milliResearch and practice in thrombosis and haemostasis102243https://www.ebi.ac.uk/biostudies/studies/S-EPMC10772875biostudies-literatureVaccine-induced immune thrombotic thrombocytopenia post COVID-19 booster vaccination in Brazil: a case series.PMC10772875Zago LTakey PRGSaraiva Pedro RFurtado BEMelo de Amorim Filho LSousa Maia MLFerreira DSBrazilian VITT Investigative Collaboration GroupPereira TDSCastro TDMJenifer da Silva Araujo Cunha JGarcez TRodrigues JVNascimento Costa NMMendes-de-Almeida DPFerreira RNunes GTMorgenstern GKFilho RCAbreu DLPietrowski Bertuol APPalm CWFreire CRBertollo Gomes Porto VMarques de Figueiredo RJulio LCMouta Nunes de Oliveira PBurger MFernandes EGKamoi TOLima Frizzera RLLignani LKGenuino de Souza TVitiello Teixeira GXavier JRGreffe NMattos de Carvalho IBise Viegas APfalseVaccine-induced immune thrombotic thrombocytopenia post COVID-19 booster vaccination in Brazil: a case series.<h4>Background</h4>The emergence of new variants of SARS-CoV-2 has led to the administration of different booster vaccines to mitigate COVID-19. Vaccines with adenoviral vectors have been rarely associated with vaccine-induced immune thrombotic thrombocytopenia (VITT).<h4>Objectives</h4>This study aimed to describe 15 cases of VITT after the third and fourth doses of the COVID-19 vaccine in Brazil.<h4>Methods</h4>Cases were reported after all kinds of anti-SARS-CoV-2 booster vaccinations between October 17, 2021, and September 4, 2022.<h4>Results</h4>Of the 26 suspected cases, 15 cases of VITT were analyzed. Of these, 10 were classified as definite VITT, 2 as probable, 1 as possible, and 2 as unlikely. The estimated frequency of definite, probable, or possible VITT was 0.33 cases per milli2023-01-01T00:00:00Z2023 Nov2026-06-01T19:54:23.151Z2025-04-06T13:12:55.468ZS-EPMC107728753819306410.1016/j.rpth.2023.102243