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

Colin R. Simpson (), Steven Kerr, Srinivasa Vittal Katikireddi, Colin McCowan, Lewis D. Ritchie, Jiafeng Pan, Sarah J. Stock, Igor Rudan, Ruby S. M. Tsang, Simon Lusignan, F. D. Richard Hobbs, Ashley Akbari, Ronan A. Lyons, Chris Robertson and Aziz Sheikh ()
Additional contact information
Colin R. Simpson: Victoria University of Wellington
Steven Kerr: The University of Edinburgh
Srinivasa Vittal Katikireddi: Public Health Scotland
Colin McCowan: University of St Andrews
Lewis D. Ritchie: University of Aberdeen
Jiafeng Pan: University of Strathclyde
Sarah J. Stock: The University of Edinburgh
Igor Rudan: The University of Edinburgh
Ruby S. M. Tsang: University of Oxford
Simon Lusignan: University of Oxford
F. D. Richard Hobbs: University of Oxford
Ashley Akbari: Swansea University
Ronan A. Lyons: Swansea University
Chris Robertson: Public Health Scotland
Aziz Sheikh: The University of Edinburgh

Nature Communications, 2022, vol. 13, issue 1, 1-7

Abstract: Abstract We investigated thrombocytopenic, thromboembolic and hemorrhagic events following a second dose of ChAdOx1 and BNT162b2 using a self-controlled case series analysis. We used a national prospective cohort with 2.0 million(m) adults vaccinated with two doses of ChAdOx or 1.6 m with BNT162b2. The incidence rate ratio (IRR) for idiopathic thrombocytopenic purpura (ITP) 14–20 days post-ChAdOx1 second dose was 2.14, 95% confidence interval (CI) 0.90–5.08. The incidence of ITP post-second dose ChAdOx1 was 0.59 (0.37–0.89) per 100,000 doses. No evidence of an increased risk of CVST was found for the 0–27 day risk period (IRR 0.83, 95% CI 0.16 to 4.26). However, few (≤5) events arose within this risk period. It is perhaps noteworthy that these events all clustered in the 7–13 day period (IRR 4.06, 95% CI 0.94 to 17.51). No other associations were found for second dose ChAdOx1, or any association for second dose BNT162b2 vaccination. Second dose ChAdOx1 vaccination was associated with increased borderline risks of ITP and CVST events. However, these events were rare thus providing reassurance about the safety of these vaccines. Further analyses including more cases are required to determine more precisely the risk profile for ITP and CVST after a second dose of ChAdOx1 vaccine.

Date: 2022
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DOI: 10.1038/s41467-022-32264-6

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