Resources On The AstraZeneca Vaccine And Blood Clots

In this post I link to the following resources on the AstraZeneca Covid-19 vaccine:

  • AstraZeneca Vaccine and Blood Clots: What Is Known So Far, NY Times, by Benjamin Mueller and  April 10, 2021
    • “In rare cases, an immune reaction has led to antibodies that caused a serious clotting disorder. But public health experts maintain the vaccine’s benefits far outweigh the risks for most people.”
  • Blood Clots Linked to AstraZeneca Vaccine Stem From Rare Antibody Reaction, NY Times, by , April 9, 2021
    • “New studies from Germany and Norway examined cases involving mostly younger people who developed serious and sometimes fatal blood disorders.”
  • AstraZeneca’s COVID-19 vaccine: EMA finds possible link to very rare cases of unusual blood clots with low blood platelets, European Medicines Agency, News 07/04/2021
    • “EMA confirms overall benefit-risk remains positive.”
  • Imaging Diagnosis of Splanchnic Venous Thrombosis [PubMed Abstract] [Full Text HTML] [Full Text PDF]. Gastroenterol Res Pract. 2015;2015:101029.
  • Clinical manifestations and imaging tools in the diagnosis of splanchnic and cerebral vein thromboses [PubMed Abstract]. Thromb Res. 2018 Mar;163:252-259.
  • Thrombotic Thrombocytopenia after ChAdOx1 nCov-19 Vaccination, April 9, 2021. DOI: 10.1056/NEJMoa2104840
    • From the Abstract
      • RESULTS
        • Of the 11 original patients, 9 were women, with a median age of 36 years (range, 22 to 49). Beginning 5 to 16 days after vaccination, the patients presented with one or more thrombotic events, with the exception of 1 patient, who presented with fatal intracranial hemorrhage. Of the patients with one or more thrombotic events, 9 had cerebral venous thrombosis, 3 had splanchnic-vein thrombosis, 3 had pulmonary embolism, and 4 had other thromboses; of these patients, 6 died. Five patients had disseminated intravascular coagulation. None of the patients had received heparin before symptom onset. All 28 patients who tested positive for antibodies against PF4–heparin tested positive on the platelet-activation assay in the presence of PF4 independent of heparin. Platelet activation was inhibited by high levels of heparin, Fc receptor–blocking monoclonal antibody, and immune globulin (10 mg per milliliter). Additional studies with PF4 or PF4–heparin affinity purified antibodies in 2 patients confirmed PF4-dependent platelet activation.CONCLUSIONS
          Vaccination with ChAdOx1 nCov-19 can result in the rare development of immune thrombotic thrombocytopenia mediated by platelet-activating antibodies against PF4, which clinically mimics autoimmune heparin-induced thrombocytopenia. (Funded by the German Research Foundation.)
      • Thrombosis and Thrombocytopenia after ChAdOx1 nCoV-19 Vaccination, April 9, 2021. DOI: 10.1056/NEJMoa2104882
        • Summary: “We report findings in five patients who presented with venous thrombosis and thrombocytopenia 7 to 10 days after receiving the first dose of the ChAdOx1 nCoV-19 adenoviral vector vaccine against coronavirus disease 2019 (Covid-19). The patients were health care workers who were 32 to 54 years of age. All the patients had high levels of antibodies to platelet factor 4–polyanion complexes; however, they had had no previous exposure to heparin. Because the five cases occurred in a population of more than 130,000 vaccinated persons, we propose that they represent a rare vaccine-related variant of spontaneous heparin-induced thrombocytopenia that we refer to as vaccine-induced immune thrombotic thrombocytopenia.
    • Antibody Responses to Natural Infection and Vaccination [Podcast]
      Supplement to the N Engl J Med 2021; 384:e65
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