I was once at a wedding on an island so pretty much all guests traveled there and stayed in the same few buildings. A teenager ended up having chickenpox and it caused a shitload of problems. Yes, the kid weathered it fine but it's a lot more dangerous for adults and that meant quarantining anyone who showed any symptoms. Great fun.
I asked the mom why they didn't vaccinate and she said "Oh you always hear all them bad things about those vaccines, you know."