In Canada. It had help, as the headline, says. We have always known one or two people on the edges of our Christian circles who did not vaccinate. Usually they are chiropractors, or closely connected to them. It's hard for me to bite my tongue. Dead children, and all that.
It is usually associated with the belief that natural things are better. That doesn't have any overlap with Christianity, but it does have some similar appeal. It seems old-fashioned, tested, safe - not like these new chemically things that have God-knows-what in them. No real basis in reality to the naturalness belief, but you can always keep the anecdotes that support your view and ignore the others. Secondly, that "naturalness" view likes the idea that God made this a simple world which man has complicated and messed with, so getting back to those simple things is a way of reversing the Fall, or at least, becoming more as God intended. Again, that's not what the Christian doctrine means, but it has the same narrative feel to it, so people who like a sort of traditional Christianity are drawn to it because it feels the same.
Of course, Buddhists and New Agey and faux Native American religion adherents could say the same. Natural. It feels right. It must be right. It's usually nice, gentle people too.
Still, there are those dead kids. Not a great tradeoff.