It is a huge percentage, but the article said "virtually all," and 80% is not virtually all. 98% is virtually all. Even 95% is virtually all. But 80% is not. This is especially true when you consider that that 80% is infected with ONE STRAND of HPV - not necessarily the super-dangerous ones that the vaccine protects - and therefore, if it can be determined what strand a person is infected with, vaccination may still be helpful in preventing infection by one of the other strands.