It protects against the 2 (16 & 18) that cause 90% of the cancers and a couple of the other strains that cause cancer as well as some that cause warts. They haven’t bothered to pay for clinical trials on the other 140 known strains but most of these are not likely to lead to cancer, and theirs no point in wasting money on clinical trials for strains that don’t have a medical necessity. But it is likely to block other strains, they just haven’t had and likely won’t have clinical trials to prove it.