Here, since Goggle search is beyond your capability.
https://www.cdc.gov/vaccinesafety/research/publications/index.html
Pick any safety study you want. General, or specific risks.
third one:
following J&J/Janssen vaccination of cerebral venous sinus thrombosis (CVST) with thrombocytopenia, which involves blood clots in the brain with low platelet counts
Yup, and the rate was so low as to be difficult to distinguish between the background noise.
