You got that one wrong with respect to Gardasil. There is no attempt to bring about herd immunity, because HPV is not eliminated by the vaccination. It's not like smallpox which was eradicated person by person. Gardasil is meant to protect (imperfectly - 50 to 70%) the individual, not the population.
I’m sorry, I was talking about vaccines “in-general” because none of the candidates was making a distinction between the normal vaccines and this one. They just said it was immoral not to let parents have the choice, and to opt-in.
But opt-in doesn’t make sense anyway — you can ALWAYS opt-in, just get the vaccine. It’s not like parents need government PERMISSION to get a vaccine, just a doctor’s prescription.