It could be something like pancreatic cancer which is generally not discovered until it starts showing symptoms in very late stages. But thats not usually considered “rare.”
We lost my cousin’s wife (who was vaxxed) 2 years ago in February to what the doctors called a rare and aggressive form of cancer. One day she was making dinner in her kitchen and 7 weeks later she was dead.
Now they are telling her husband my cousin (who was vaxxed) that he has a rare form of blood cancer with no treatment and may only have 36 months to live.