PubMed is your friend. Although recentish titles have been about if it's worth vaccinating boys with HPV from an economic perspective, the fact that the vaccine is currently less than 90% effective when cervical growths are biopsied (90% the predicted maximum with boys and girls having an over 75% take up rate for the vaccine)... nothing on if HPV does actually cause cancer, nor on side effects that I can see.

But then I am not making this decision now so I'm not spending ages researching something that may have different findings in a few years when it is suggested for Liebs, if it ever is for boys where I live.