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Fair enough, but some people feel similarly about vaccines: that it's outrageous that the efficacy or safety of vaccines are questioned, and that it has the potential - if that questioning continues and snowballs - for many, many lives to be lost as certain diseases make a comeback.

That's a fair point, and I'm sure it could be argued that in principle this is similar to HIV/AIDS denialism. However, although I don't know much about the anti-vaccine arguments, my impression is that they have a lot to do with concern over possible side-effects. Such concerns seem less intrinsically unreasonable to me than actually denying that HIV is responsible for AIDS. And of course, in practical terms, HIV/AIDS denialism is believed to have cost huge numbers of lives in Africa.