Clotting issues can also come from other factors like the birth control pill. I believe the 6 cases involving the JNJ vax were between 18 & 35. So I’d be asking that question, too.
Shortly after these problems started to surface, researchers in Germany and Norway quickly identified an autoantibody called platelet factor 4 antibody that appeared to be linked to the syndrome. Platelet factor 4 antibody causes heparin-induced thrombocytopenia (HIT), a rare clotting disorder that affects 1%-2% of people after exposure to heparin. In rare cases, platelet factor 4 antibody has been associated with CVST.
On April 9 2021, the German team lead by Andreas Greinacher, MD, PhD, of the Medical University of Greifswald in Germany, published a case series about the issue in the New England Journal of Medicine. It included 11 patients in Germany and Austria who presented with unusual thromboses and moderate to severe thrombocytopenia, five to 16 days after receiving the AstraZeneca vaccine. None of these patients had received heparin in the past. Nine were women, and the median age was 36 (range 22-49). Five patients had more than one clotting event: nine had CVST, three had splanchnic vein thrombosis, three had pulmonary embolism, four had other thromboses, and five had disseminated intravascular coagulation (DIC). Six patients died.
The researchers also did platelet activation assays on 28 patients who developed thrombosis and thrombocytopenia after receiving the AstraZeneca vaccine, and who tested positive for antibodies against platelet factor 4. Results showed increased platelet activation in the presence of platelet factor 4, which was inhibited with immune globulin.
Greinacher and colleagues wrote that the disorder “resembles” severe HIT, but “unlike the usual situation” none of these patients received heparin in the past. They noted that autoimmune or spontaneous HIT can occur without exposure to heparin, and is characterized by “unusually severe thrombocytopenia, increased rates of DIC and atypical clots.” They concluded that the AstraZeneca vaccine can result in a rare syndrome that “clinically mimics autoimmune heparin-induced thrombocytopenia,” and propose using the term “vaccine induced immune thrombotic thrombocytopenia” (VITT) to avoid confusion.
I’m also thinking that Vitamin B6 could be a factor.