key: cord-0950481-sicmjkgt authors: Smadja, David M.; Yue, Qun-Ying; Chocron, Richard; Sanchez, Olivier; Lillo-Le Louet, Agnes title: Vaccination against COVID-19: insight from arterial and venous thrombosis occurrence using data from VigiBase date: 2021-04-16 journal: Eur Respir J DOI: 10.1183/13993003.00956-2021 sha: c9874927faaba7ddf2616f5075fbeef613a0bd88 doc_id: 950481 cord_uid: sicmjkgt we observed an imbalance between venous and arterial thrombotic events in mRNA vaccines while with AZ1222 they are evenly shared. Our analysis highlights cerebral vein thrombosis with the three vaccin. Second, the best way to evaluate thrombotic events in the vaccinated population should be to match to unvaccinated controls in a 1:1 ratio according to demographic and clinical characteristics (14) . However, ADRs reported in VigiBase do not allow us to have this kind of paired data. Third, we could have an unusual reporting because of the novelty of the vaccine. Indeed, studies design may modify reporting of ADRs (15) . Open-label studies have been described to overestimate the risk of vascular adverse events by at least 50% in contrast to double blind randomized trials (15) . Pharmacovigilance spontaneous reporting is different from clinical trials but probably close to open-label studies for potential unusual estimation of thrombotic events that could be influenced by novelty of the drug, media interest and/or conflicting results in literature. All in all, our data represents a hypothesis-generating study suggesting that thrombotic events, including CVT, might occur in association with all three vaccines, but this hypothesis requires further investigations including extensive clinical and biological studies. Benefits of the vaccine is a non-discussion point in COVID-19 outbreak epidemiology. However there is an urgent need for a prospective evaluation of coagulopathy and thrombotic events to fathom rare but serious side effects after COVID-19 vaccination and better characterize VIPIT and other thrombocytopenia associated or not with thrombotic events after the three vaccines. Funding: David M. Smadja'COVID team has been funded with grants from the French national agency for research ANR SARCODO (Fondation de France) and Mécénat Covid AP-HP. All authors declare that they have no conflict of interest related to this work. Acknowledgement: this publication describes information obtained from VigiBase. VigiBase, has information coming from a variety of sources, and the probability that the suspected adverse effect is drug-related is not the same in all cases. This information does not represent the opinion of the UMC or the World Health Organization. Circulating Von Willebrand factor and high molecular weight multimers as markers of endothelial injury predict COVID-19 in-hospital mortality Prevalence of pulmonary embolism in patients with COVID 19 at the time of hospital admission Endothelial cell dysfunction: a major player in SARS-CoV-2 infection (COVID-19)? Anticoagulation prior to hospitalization is a potential protective factor for COVID-19: insight from a French multicenter cohort study A Bayesian neural network method for adverse drug reaction signal generation Pandemic influenza A H1N1 vaccines and narcolepsy: vaccine safety surveillance in action Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine Efficacy and Safety of the mRNA-1273 SARS-CoV-2 Vaccine Single-dose administration and the influence of the timing of the booster dose on immunogenicity and efficacy of ChAdOx1 nCoV-19 (AZD1222) vaccine: a pooled analysis of four randomised trials Thrombotic Thrombocytopenia after ChAdOx1 nCov-19 Vaccination Thrombosis and Thrombocytopenia after ChAdOx1 nCoV-19 Vaccination Under-reporting of adverse drug reactions : a systematic review BNT162b2 mRNA Covid-19 Vaccine in a Nationwide Mass Vaccination Setting Statistical controversies in clinical research: limitations of open-label studies assessing antiangiogenic therapies with regard to evaluation of vascular adverse drug events-a meta-analysis