Anyway, the reason for mandating any vaccine would be to protect the health of the community. So let's look at this from a public health standpoint...

It is important to vaccinate school children because schools locations of dense population. In short, a lot of people are in school, and they interact and possibly spread disease. For example, dangerous infections like diphtheria spread through casual contact and proximity. So it's important to vaccinate against those kinds of diseases because schools can be a hotbed of their spread.

Now consider HPV. HPV is a pretty bad virus. Causes genital warts, cervical cancer, penile cancer and anal cancer. It's common, too: 80% of US adults will have come into contact with HPV at some point, and right now it is estimated that 25% of US women have an active infection. But how does it spread? It spreads through skin contact, specifically sexual friction (penetration and fluids NOT REQUIRED). While most young folks find their sexual partners at school, and the sexual activity pool is remarkably shallow in that environment, the way HPV spreads isn't by casual contact. You don't get HPV by sitting in a classroom next to an infected person.

Because it takes a little more than casual contact to spread hPV, it's not the kind of public health hazard that requires mandatory vaccination for school enrollment.

Don't get me wrong, though. It is extremely important to vaccinate kids for HPV while they're young (girls should get it now, boys will have to wait till the drug is approved for their use). Cancer is a pretty horrible illness, and I wouldn't wish it on anybody. Worldwide, cervical cancer is a leading cause of death among women. Cancer is a public health problem because of its significant economic and social impact. If we can protect people against this disease, then why shouldn't we?