About 5 years ago, in Canada, chicken pox (varicella) vaccination because mandatory in schools.

While researching to see if I would get the shots for my kids I learned that natural cases of chicken pox act as boosters in adults who have already had chicken pox, and that simply being around vaccinated children does not have the effect.

This means that adults who have had chicken pox, and think themselves safe, have actually been undermined by the vaccination program and may be at higher risk of reinfection.

This is not at odds with your info; they stack.