To be more emphatic than glupson. No, the mRNA vaccines, namely the Pfizer and Moderna vaccines, cannot and do not cause clots. The adenovirus-based vaccines do have that potential, but despite the hysteria in the press, it is a very rare adverse event, which of course is no comfort if you happen to be one of the rare cases. One diagnostic sign of the adeno-vaccine induced clotting is elevated D-dimers (a degradation product of the clotting factor fibrinogen), which Peter does report, but that also happens with COVID-induced clotting. However, the vaccine-induced mechanism starts with a marked reduction in platelet count by an auto-immune mechanism, which separates it from the COVID-induced phenomenon. The adeno-vaccine induced clotting mechanism has now been defined in the context of several reports that occurred in the New England Journal of Medicine in the last two weeks. Turns out, it can be successfully treated if recognized early enough, but that's the trick. It's so rare that routine screening is not (yet) done. Look for that in future, because it will be hard to do completely without the J&J vaccine. The AstraZeneca adeno vaccine has many other problems, as well.
