The recent concerns about the adenovirus vector vaccine and clotting is of some interest. The above is the classic clotting mechanism as studied in First Year Med School. In reality it is much more complex but the above gives some insight. The problem is that not everyone is the same and small genetic differences can exacerbate clotting, namely reduce or increase it.
Several articles in NEJM have recounted clinical evidence. The first notes:
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.
and the second notes:
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.
It appears that a specific Ab is the cause. We had addressed this issue a while back. The issue then is; doe we now tests for the Ab factor or do we try to find what the adenovirus does to start the thrombotic chain?
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