I don't understand why anyone would be against vaccines, with one exception: parents who have a kid that actually suffered from one of the super rare side effects. For example I have seen a documentary about pro/contra vaccine, where one person featured was a child who had gotten polio as a result of the polio vaccine.
My sister was unable receive a full set of vaccinations due to a bad allergic reaction, which makes my parents even more pro vaccines because she relies on herd immunity
I feel like it's a bit like terminally ill people suddenly finding religion. Parents with autistic children are desperate to find something to blame or believe in for their situation. So, they've latched onto this absolute fiction that vaccination can cause autism. Nevermind it was something like a single study done that has since been completely disproved. Notice Nicholas up there has an "older, vaccine injured sibling".