And really you'd want to know when some threshold of adoption had been reached.

Undisciplined

Indeed. I tried to find a date of introduction of vaccines in Brazil and found the seventies according to one English source. So my very quick conclusion was that there is not even correlation in his graph. However just one random source is not enough and it was not an official source in Portuguese so I am not sure.
For transparency my source is:
https://www.scielo.br/j/csp/a/XxZCT7tKQjP3V6pCyywtXMx/?lang=en
It says 1973, but it would require more investigation to be sure.

john_doe

health

Childhood Vaccine Schedule Thoughts and Questions

Also, wealthier families can afford better medical treatments, so their kids survive infections more often.

It would be much more informative to see when some of the big vaccines were introduced, so that we could see if it corresponds to anything on the graph.