PF4 and deep vein thrombosis: In Kolahchi et al., reportedly 22 cases (51.1% of that study’s cohort) developed AIS associated with the vaccine-induced immune thrombotic thrombocytopenia (VITT; thrombocytopenia and antibodies against platelet factor 4 leading to thrombosis) four weeks after all, except one patient, received a viral vector vaccine out of > 1.3 billion (< 0.000%) COVID-19 administered vaccinations from December, 2020, to December, 2021 [47,49].