IDIAPJGol researchers study the risk of thrombotic events after infection and vaccination against COVID-19
The study includes data from 2.6 million vaccinated people, 174,000 cases of COVID-19 and 4.5 million people from the general population..
A new IDIAPJGol study compares the incidence rates of thrombotic events after vaccination with Pfizer and AstraZeneca and after COVID-19 infection with the rates observed among the general population before the COVID-19 pandemic using data from the historic electronic clinic of Primary Care of Catalonia.
Venous and arterial thromboembolism events
In the first 21 days after a first dose of Pfizer, a slightly higher than expected number of cases of venous thromboembolism (VT, a composite of pulmonary embolism and deep vein thrombosis) were observed. Specifically, 313 cases were observed (versus 264 expected). VT cases after a second dose of Pfizer and after the first dose of AstraZeneca were less than or the same as expected. In contrast, in people infected with COVID-19, VT rates were 10 times higher than expected (630 observed cases vs. 61 expected).
Arterial thromboembolism (AT, a composite of myocardial infarction and ischemic stroke) rates after vaccination were similar to the rates expected for both vaccines. In contrast, in people with COVID-19, the BP rates were 10 times higher than expected (683 observed cases vs. 165 expected).
After the first and second doses of Pfizer and the first dose of AstraZeneca, between 1.3 and 1.5 more cases of thrombocytopenia were observed than expected. In contrast, among people with COVID-19, 5 times more cases of thrombocytopenia than expected were observed (2,476 cases vs. 560 expected). In addition, people with COVID-19 had 12 times more cases of VT with thrombocytopenia and 5 times more cases of AT with thrombocytopenia than expected.
Elena Roel, one of the main researchers of the study, concludes that “the results show that the vaccines against COVID-19 have a similar safety profile. Instead, the rates of thrombotic events were much higher than expected in people with COVID-19." Therefore, "this study reinforces the importance of vaccination against COVID-19 as a primary tool in preventing the adverse effects of the COVID-19 disease," highlights Talita Duarte-Salles, one of the coordinators of the study.
Thrombosis and thrombocytopenia after vaccination against and infection with SARS-CoV-2 in Catalonia, SpainEdward Burn, Elena Roel, Andrea Pistillo, Sergio Fernández-Bertolín, Maria Aragón, Berta Raventós, Carlen Reyes, Katia Verhamme, Peter Rijnbeek, Xintong Li, Victoria Y. Strauss, Daniel Prieto-Alhambra & Talita Duarte-Salles.