First-dose ChAdOx1 and BNT162b2 COVID-19 vaccines and thrombocytopenic, thromboembolic and hemorrhagic events in Scotland
Open Access
- 9 June 2021
- journal article
- research article
- Published by Springer Science and Business Media LLC in Nature Medicine
- Vol. 27 (7), 1290-1297
- https://doi.org/10.1038/s41591-021-01408-4
Abstract
Reports of ChAdOx1 vaccine–associated thrombocytopenia and vascular adverse events have led to some countries restricting its use. Using a national prospective cohort, we estimated associations between exposure to first-dose ChAdOx1 or BNT162b2 vaccination and hematological and vascular adverse events using a nested incident-matched case-control study and a confirmatory self-controlled case series (SCCS) analysis. An association was found between ChAdOx1 vaccination and idiopathic thrombocytopenic purpura (ITP) (0–27 d after vaccination; adjusted rate ratio (aRR) = 5.77, 95% confidence interval (CI), 2.41–13.83), with an estimated incidence of 1.13 (0.62–1.63) cases per 100,000 doses. An SCCS analysis confirmed that this was unlikely due to bias (RR = 1.98 (1.29–3.02)). There was also an increased risk for arterial thromboembolic events (aRR = 1.22, 1.12–1.34) 0–27 d after vaccination, with an SCCS RR of 0.97 (0.93–1.02). For hemorrhagic events 0–27 d after vaccination, the aRR was 1.48 (1.12–1.96), with an SCCS RR of 0.95 (0.82–1.11). A first dose of ChAdOx1 was found to be associated with small increased risks of ITP, with suggestive evidence of an increased risk of arterial thromboembolic and hemorrhagic events. The attenuation of effect found in the SCCS analysis means that there is the potential for overestimation of the reported results, which might indicate the presence of some residual confounding or confounding by indication. Public health authorities should inform their jurisdictions of these relatively small increased risks associated with ChAdOx1. No positive associations were seen between BNT162b2 and thrombocytopenic, thromboembolic and hemorrhagic events.Keywords
Funding Information
- DH | National Institute for Health Research
This publication has 32 references indexed in Scilit:
- The UK's pandemic influenza research portfolio: a model for future research on emerging infectionsThe Lancet Infectious Diseases, 2019
- Misdiagnosis of primary immune thrombocytopenia and frequency of bleeding: lessons from the McMaster ITP RegistryBlood Advances, 2017
- Autoimmune heparin‐induced thrombocytopeniaJournal of Thrombosis and Haemostasis, 2017
- Evaluating the effectiveness, impact and safety of live attenuated and seasonal inactivated influenza vaccination: protocol for the Seasonal Influenza Vaccination Effectiveness II (SIVE II) studyBMJ Open, 2017
- Five key recommendations for the implementation of Hospital Electronic Prescribing and Medicines Administration systems in ScotlandJournal of Innovation in Health Informatics, 2017
- The REporting of studies Conducted using Observational Routinely-collected health Data (RECORD) StatementPLoS Medicine, 2015
- The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Statement: Guidelines for reporting observational studiesInternational Journal of Surgery, 2014
- Immune thrombocytopenic purpura (ITP) associated with vaccinations: a review of reported casesImmunologic Research, 2014
- Vaccine administration and the development of immune thrombocytopenic purpura in childrenHuman Vaccines & Immunotherapeutics, 2013
- Four different study designs to evaluate vaccine safety were equally validated with contrasting limitationsJournal of Clinical Epidemiology, 2006