• No peer-reviewed study or pharmacovigilance database reports a 3,000-fold increase in brain-clot risk after COVID-19 vaccination compared with flu shots; the figure appears to be fabricated or a distortion of existing misinformation.
• Fact-checkers have debunked the related claim that COVID-19 vaccines are “112,000% more likely” (1,120 times) to cause brain clots than flu vaccines. That number originated from a paper by vaccine opponents who calculated a proportional reporting ratio (PRR) from unverified, self-reported VAERS data; a PRR measures reporting disproportionality, not actual risk or incidence, and VAERS lacks a true denominator and is subject to severe reporting bias ¹²³⁴.
• A large Oxford study of 81 million electronic health records found cerebral venous thrombosis (CVT) after mRNA COVID-19 vaccination was extremely rare (4 per 1 million) and the rate in 172,742 flu patients was 0 per 1 million; the risk from COVID-19 infection itself was 8–10 times higher than from the vaccine ⁵.
• A controlled retrospective cohort directly comparing COVID-19 and influenza vaccines found stroke incidence was not significantly different (3 vs 2 per 10,000) and the overall 30-day thrombotic event rate was about 12 per 10,000 vs 6 per 10,000, an adjusted hazard ratio of roughly 2—not 3,000 ⁶.
• FDA analyses of Medicare claims found no increased stroke risk in the overall senior population after COVID-19 vaccination alone; a small safety signal observed when high-dose flu and COVID vaccines were given together to adults 85+ translated to roughly 3 events per 100,000 doses ⁷⁸.

Overall validity: 5%

1. COVID‑19 vaccines increase the risk of delusions 50 times compared with flu shots.
2. Are COVID vaccines causing more blood clots? | Voices For Vaccines
3. Misleading to say brain clots '112000% more likely' after ... - AAP
4. Dubious VAERS study links COVID-19 vaccines to blood clots - Public Health Communications Collaborative
5. Study: COVID much more likely than vaccines to cause blood clots | CIDRAP
6. Thrombotic events following Covid-19 vaccines compared to Influenza vaccines
7. Local 12: Study: COVID-19, flu shots may increase stroke risk in seniors when given together - University of Cincinnati: Founder of Co-op, Leader in Co-op | University of Cincinnati
8. Covid shots may slightly increase risk of stroke in older adults, particularly when administered with certain flu vaccines | CNN