I wondered if it started with the MMR vaccine. I never had the MMR because I had rubella as a toddler so I got the “pass”. I was also lucky enough to never have received the polio vax because it was stopped the year I would’ve been required to receive it where we lived. I recently asked my mother what vaccines I had as a child and she could not remember any. Now I feel guilty for allowing my children to have followed the recommended vaccines back in the 80s and 90s.