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First-dose ChAdOx1 and BNT162b2 COVID-19 vaccines and thrombocytopenic, thromboembolic and hemorrhagic events in Scotland

C. R. Simpson, T. Shi Orcid Logo, E. Vasileiou, S. V. Katikireddi Orcid Logo, S. Kerr, E. Moore, C. McCowan, U. Agrawal, S. A. Shah Orcid Logo, L. D. Ritchie, J. Murray, J. Pan, D. T. Bradley Orcid Logo, S. J. Stock Orcid Logo, R. Wood, A. Chuter, J. Beggs, H. R. Stagg, M. Joy, R. S. M. Tsang Orcid Logo, S. de Lusignan Orcid Logo, R. Hobbs, Ronan Lyons Orcid Logo, Fatemeh Torabi Orcid Logo, Stuart Bedston, M. O’Leary, Ashley Akbari Orcid Logo, J. McMenamin, C. Robertson, A. Sheikh Orcid Logo

Nature Medicine, Volume: 27, Issue: 7, Pages: 1290 - 1297

Swansea University Authors: Ronan Lyons Orcid Logo, Fatemeh Torabi Orcid Logo, Stuart Bedston, Ashley Akbari Orcid Logo

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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 even...

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Published in: Nature Medicine
ISSN: 1078-8956 1546-170X
Published: Springer Science and Business Media LLC 2021
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa57111
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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.
College: Faculty of Medicine, Health and Life Sciences
Funders: MC_PC_19004/MRC_/Medical Research Council/United Kingdom MC_PC_19075/MRC_/Medical Research Council/United Kingdom MC_PC_13043/MRC_/Medical Research Council/United Kingdom MR/K006525/1/MRC_/Medical Research Council/United Kingdom MC_PC_20058/MRC_/Medical Research Council/United Kingdom
Issue: 7
Start Page: 1290
End Page: 1297