Thrombosis and Thrombocytopenia after ChAdOx1 nCoV-19 Vaccination
Article reports 5 Norwegian cases (age 32 to 54 years) of severe venous thrombosis and thrombocytopenia 7 to 10 days after first vaccine dose, all whom had high level of antibodies to platelet factor 4–polyanion complexes, but no previous exposure to heparin.
Source:
New England Journal of Medicine
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SPS commentary:
Four of the patients had severe cerebral venous thrombosis with intracranial haemorrhage, and the outcome was fatal in three. The authors suggest their findings indicate a shared pathophysiological basis of the condition in these five patients and should raise awareness that a syndrome similar to autoimmune heparin-induced thrombocytopenia may occur in some persons after vaccination with ChAdOx1 nCoV-19. They add that by providing a link between thrombosis and the immune system, these results strengthen the view that vaccination may have triggered the syndrome. They note that treating severely ill patients such as those described in this report is always challenging, and the most important implication of the current findings is that clinicians should have a low threshold for requesting ELISA testing for PF4–polyanion antibodies, including confirmatory functional testing, in patients who have unexpected symptoms after vaccination.
This is one of two reports in the New England Journal of Medicine that provides detailed observations of patients who developed thrombotic thrombocytopenia after receiving the AstraZeneca vaccine and have speculated about a possible mechanism. The other report describes 11 German/Austrian pts (9 women; median age 36 years) who developed immune thrombotic thrombocytopenia mediated by platelet-activating antibodies against PF4, which clinically mimics autoimmune heparin-induced thrombocytopenia, 5 to 16 days after vaccination.