Perhaps some lawyers here can opine: Is it not possible for some of those affected by the recent measles outbreak, and others adversely impacted, to file a class action against the anti-vaxxers ? Call me paranoid, but lately I've been thinking about getting the MMR as an adult who is in mid 40s - and I'm pissed. So, I can't even imagine what someone who is directly impacted might be feeling.
Aren't you only affected by the measles outbreak if you're an anti-vax in the first place... ?
Also, the anti-vaxxer who is affected can argue they were misled or misinformed, or if they are children of anti-vaxxers, not anti-vaxxer themselves. Many possibilities..
Disclaimer: IMNAL.