I think it was Alex Jones who maintained a narrative Sandy Hook massacre was a hoax, he was sued by victims, is there a legal presidence for anyone who gets cervical cancer and fell for the anti-vax mob to sue THEM for damages.
If what is said here can be backed more widely then thereis surely some degree of liability. If Madonna can be sued for keeping fans waiting for 2 hours (or something) at a concert, then anti vaxers can also be sued. Esp in the US where medical care has to be paid for.