It has only been targeted against the strains known to cause cancer. I haven't looked but I would guess getting all strains would have been a greater challenge,

It has only been targeted against the strains known to cause cancer. I haven't looked but I would guess getting all strains would have been a greater challenge, and would not have greatly increased uptake of the vaccine. The false perception that it's a vaccine that will encourages unprotected sex has already greatly hindered adoption in the US.