And who has the records of which vaccine someone had administered in the late 50's? For that matter, who has the records of who received the Sabin vaccine in the early 60's when it was administered at clinics held in the public schools for the general population?
That disclaimer means absolutely nothing.
I received the Salk vaccine at a state children's hospital in 55. I didn't have polio but was witness to some vicious rehab of the kids who did.