In a somewhat similar matter, many years ago I diagnosed a patient with chickenpox (prior to the US vaccine IIRC.) His parents told me they were planning to fly to Florida for a vacation. I told them not to do that. I later learned they flew the extremely contagious kid there commercially in spite of me. It could have been fatal to some "Make a Wish" kid traveling to Disney. How would you like your kid invited to a chickenpox party without your consent AND against the "hosting kid's" doctor's explicit advice? If you were aware of the source and your child suffered serious consequences as a result wouldn't you be furious? Furious enough to enough to run it by a lawyer? Might not the well known nature of chickenpox be enough to argue that taking a child with known chickenpox on a plane was an irresponsible act for a lay person, much less a lay person who'd been explicitly warned against it by a doctor? Parents holding booze parties for underaged children get sued when a drunk kid gets in an accident driving home thereafter. Is flying with known chickenpox any less negligent? I'm not saying there should be liability for all anti-vax choices, but that there could be in some circumstances. Parents deserve broad, but not absolute and total deference for their parenting choices.