Alliance for Pandemic Preparedness

May 10, 2021

Meta-Analysis of Risk of Vaccine-Induced Immune Thrombotic Thrombocytopenia Following ChAdOx1-S Recombinant Vaccine

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  • [Pre-print, not peer-reviewed] Pooled estimates of vaccine-induced immune thrombotic thrombocytopenia (VITT) cumulative incidence among individuals who received Oxford-AstraZeneca/Covishield vaccine in 10 countries found an overall risk of 1 in 139,000. For those aged 65 and over, the risk was about 1 in 1,000,000, while for those under 55, the risk was between 1 in 20,000 to 60,000. Risk also varied between countries in the analysis, with a cumulative incidence of 1.67 per 100,000 in the UK, and 5.06 per 100,000 in Norway. The authors note that even the highest reported incidence in Norway is lower than the risk of serious COVID-19 outcomes in areas with high community spread, as well as risk of serious injury requiring hospitalization or death as a result of driving.

Chan et al. (May 8, 2021). Meta-Analysis of Risk of Vaccine-Induced Immune Thrombotic Thrombocytopenia Following ChAdOx1-S Recombinant Vaccine. Pre-print downloaded May 10 from https://doi.org/10.1101/2021.05.04.21256613