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

Colin R Simpson* (Corresponding Author), Steven Kerr, Srinivasa Vittal Katikireddi, Colin McCowan, Lewis D Ritchie, Jiafeng Pan, Sarah J Stock, Igor Rudan, Ruby S M Tsang, Simon de Lusignan, F D Richard Hobbs, Ashley Akbari, Ronan A Lyons, Chris Robertson, Aziz Sheikh* (Corresponding Author)

*Corresponding author for this work

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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.

Original languageEnglish
Article number4800
Number of pages7
JournalNature Communications
Volume13
DOIs
Publication statusPublished - 15 Aug 2022

Bibliographical note

Acknowledgements
EAVE II is funded by the Medical Research Council (MR/R008345/1) with the support of BREATHE—The Health Data Research Hub for Respiratory Health [MC_PC_19004], which is funded through the UK Research and Innovation Industrial Strategy Challenge Fund and delivered through Health Data Research UK. This research is part of the Data and Connectivity National Core Study, led by Health Data Research UK in partnership with the Office for National Statistics and funded by UK Research and Innovation (grant ref MC_PC_20058). Additional support has been provided through Public Health Scotland and Scottish Government DG Health and Social Care. FDRH acknowledges part support as Director of the NIHR Applied Research Collaboration (ARC) Oxford Thames Valley, and Theme Lead of the NIHR OUH BRC. We thank Dave Kelly from Albasoft Ltd for his support with making primary care data available and Frances Burns, Mathhew Thankur, Wendy Inglis-Humphrey, Vicky Hammersley, Dom Balharry and Laura Brook, Morag Edwards and Laura Gonzalez Rienda for their support with project management and administration. We thank the EAVE II Public Advisory Group. Our thanks to Prof. Jenni Quint, Prof. Rustam Al-Shahi Salman and Dr. Quentin Hill for their help with reviewing code lists.

Data Availability Statement

A data-dictionary covering the datasets used in this study can be found at https://github.com/EAVE-II/EAVE-II-data-dictionary. Patient-level data underlying this article is controlled and cannot be shared publicly due to data protection and confidentiality requirements. Data can be made available to approved researchers for analysis after securing relevant permissions from the data holders via the Public Benefit and Privacy Panel (PBPP). Enquiries regarding data availability should be directed to phs.edris@phs.scot. The normal expectation is that the application process will be concluded within 30 working days of submission, not including any time that has elapsed while waiting for a response.

Code availability
All code used in this study is publicly available at https://github.com/EAVE-II/Covid-vaccine-safety-haemo.

Keywords

  • Adult
  • BNT162 Vaccine
  • COVID-19/epidemiology
  • COVID-19 Vaccines/adverse effects
  • Humans
  • Prospective Studies
  • Purpura, Thrombocytopenic, Idiopathic/epidemiology
  • Scotland
  • Thromboembolism/epidemiology
  • Vaccination/adverse effects

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