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The Story Behind COVID Vaccines and Brain Blood Clots

Rob Orman, MD

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The news this week has been replete with stories about increased clot risk in those who have received the AstraZeneca and Johnson & Johnson COVID-19 vaccines. In this episode, we break down: what we know so far about vaccine induced thrombotic thrombocytopenia (VITT), the research that has revealed an underlying mechanism, CDC and NHS recommendations, and a primer on cerebral venous thrombosis -- the primary clot site associated with VITT.

We Discuss:


Vaccine-induced thrombotic thrombocytopenia (VITT)


  • The similar mechanism of AstraZeneca's and Johnson & Johnson's COVID-19 vaccines [01:00];
  • Proposed mechanism of VITT [03:20];
  • Types of clots associated with VITT [04:00];
  • Incidence of VITT in the US and UK [05:00];
  • The CDC and NHS rallying cry to treat this differently that other causes of cerebral venous thrombosis (CVT) [06:30];
  • The UK algorithm for evaluating and managing patients with suspected VITT [08:00];


A primer on CVT


  • Why CVT can cause problems [10:30]
  • Presenting symptoms of CVT [11:00]
  • Physical exam findings and the sensitivity of papilledema [15:00]
  • Using D-dimer in the evaluation of CVT [16:50];
  • A new clinical score for CVT [19:00];
  • Utility of spinal tap as a rule-out test [21:00];
  • Imaging options (CT venogram vs MR venogram) [22:00];
  • CDC treatment recommendations for  VITT associated CVT and how it’s different than most other CVT’s [25:00];
  • Testing patients with VITT for heparin-PF4 antibodies and how that may guide whether or not to use IVIG [26:35].


Posted 4/16/21



  1. Greinacher, Andreas, et al. "Thrombotic Thrombocytopenia after ChAdOx1 nCov-19 Vaccination." New England Journal of Medicine (2021). PDF
  2. Brief Report: Thrombosis and Thrombocytopenia after ChAdOx1 nCoV-19 Vaccination PDF
  3. Spadaro, Anthony, et al. "Cerebral venous thrombosis: Diagnosis and management in the emergency department setting." The American Journal of Emergency Medicine (2021).
  4. Ferro, José M., et al. "European Stroke Organization guideline for the diagnosis and treatment of cerebral venous thrombosis–endorsed by the European Academy of Neurology." European stroke journal 2.3 (2017): 195-221.
  5. Tanislav, Christian, et al. "Cerebral vein thrombosis: clinical manifestation and diagnosis." BMC neurology 11.1 (2011): 1-5.
  6. Heldner, Mirjam R., et al. "Prediction of cerebral venous thrombosis with a new clinical score and D-dimer levels." Neurology 95.7 (2020): e898-e909.
  7. Padmanabhan, Anand, et al. "IVIg for treatment of severe refractory heparin-induced thrombocytopenia." Chest152.3 (2017): 478-48
  8. UK case breakdown Here
  9. CDC and FDA Statement Here
  10. CDC full slide deck Here
  11. Guy and St Thomas NHS VITT Pathway Here (Note, this is only an example of one way of approaching this issue. It is based on early data and expert opinion.)
  12. St. Emlyn’s has a beautiful write on on VITT Here

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