BACKGROUND AND PURPOSE:

• Schultz et al. (NEJM, 2021) describes 5 cases of severe thrombosis and thrombocytopenia following vaccination with the ChAdOx1 (AstraZeneca) COVID-19 vaccine

METHODS:

• Case reports
• Setting
  • Oslo University Hospital, Norway
• Cases included
  • 5 healthcare workers
  • 32 to 54 years old
• Study design
  • Serum antibodies tested (ELISA)
    • Platelet factor 4 (PF4)-polyanion complexes
    • SARS-CoV-2 spike and nucleocapsid proteins

RESULTS:

• 4 patients had severe cerebral venous thrombosis with intracranial hemorrhage | Fatal in 3 patients
• At time of admission
  • Levels of D-dimer were elevated in all patients
  • Screening for thrombophilia with proteins C and S and antithrombin was negative
• Platelet immunologic testing
  • All five patients had high levels of IgG antibodies to PF4–polyanion complexes
  • Platelets in serum from Patients 1, 3, 4, and 5 were clearly activated in the absence of added heparin
• All patients were negative for SARS-CoV-2 antibodies, suggesting previous infection was unlikely

CONCLUSION:

• 5 individuals developed severe venous thromboembolism in unusual sites and concomitant thrombocytopenia 7 to 10 days after vaccination (AstraZeneca)
• All 5 patients had a high level of antibodies to PF4–polyanion complexes
• The authors suggest

…that these cases represent a vaccine-related variant of spontaneous heparin-induced thrombocytopenia that we refer to as vaccine-induced immune thrombotic thrombocytopenia (VITT)

Learn More – Primary Sources:

Thrombosis and Thrombocytopenia after ChAdOx1 nCoV-19 Vaccination