Could the Covid mRNA vaccines have caused my stroke and brain abscess

The short version: a plausible mechanism exists, but the evidence for a direct link between the mRNA vaccine and your specific outcomes—stroke and brain abscess—is thin and circumstantial.

The evidence you have is a collection of case reports and reviews that show the mRNA vaccines can trigger serious clotting and autoimmune events. One case report describes a 22-year-old healthy male who developed antiphospholipid syndrome (APS) with a large pulmonary embolus after his second mRNA dose [2, 4]. APS is a condition where the immune system attacks clotting proteins, making the blood hypercoagulable—it clots too easily. Another case report describes a 28-year-old man who developed vaccine-induced immune thrombotic thrombocytopenia (VITT) after a booster, with severe clotting and a platelet count of 34 (normal is 143-349) [7]. A third case report describes a 34-year-old man who died from an aortic dissection 16 days after his first dose, with autopsy showing vaccine-derived spike protein in the tissue [6]. These are not common events, but they are documented.

A stroke is a clot or bleed in the brain. A brain abscess is a pocket of infection. The mechanism that connects the vaccine to a stroke is plausible: if the vaccine triggers APS or VITT, a clot could form and travel to the brain. The evidence for a brain abscess is weaker. The vaccine is not known to directly cause bacterial infections. An abscess usually follows a separate event—a dental infection, sinusitis, or a procedure that lets bacteria into the brain. If the vaccine caused a stroke that then became infected, that is a two-step chain, not a direct effect. The evidence does not include a single case of brain abscess after mRNA vaccination.

The evidence here is all case reports and narrative reviews. There are no large controlled studies comparing stroke or brain abscess rates in vaccinated versus unvaccinated people. The studies that do exist focus on myocarditis, not neurological events [1, 3, 5]. The absence of a large safety study with neurological endpoints is a gap, not proof of safety. But the gap also means the link between the vaccine and your specific outcomes is not established.

My call: the vaccine could have contributed to a clotting event that led to a stroke, but the evidence for a brain abscess is absent. Confidence: low for stroke, very low for brain abscess.