My brother born in ‘45 caught it at around age 5-7. His upper arm is about the diameter of his wrist, but that same forearm is huge. I guess post-polio syndrome is affecting people. He absolutely hated therapy and refused to exercise in any capacity afterward (but he’s lean and fit otherwise.) My older siblings wonder if he caught it from taking a sip of water from a horse trough, when they were visiting a local farm.
My cousin lived her entire life, after getting polio, with a crippled leg and lung issues. She died a couple of years ago after living a full life, having been widowed, and survived by two kids and four grandchildren. She traveled the world.
Vaccines are a Godsend most of the time but not all of the time.