Deeply offensive doesn't mean illegal. Unless there's a law that you can point at which bans this, there's no point in hiring lawyers because any challenge will be immediately thrown out. The real issue here in my view is that Facebook - a private company with no legal requirement to keep publishing anything that people post - is becoming the de facto news source for vast numbers of people. And, God help me, I have some sympathy for Facebook here if, as another commenter says, this study is being taken out of context and being used to push anti-vax conspiracy theories. It's such a complex issue.