I am assuming they meant it won't clear one strain that you already have but may protect against another one you don't

Yes, I understand that. Would you mind reading my comment above? The thing I’m confused about is why it won’t protect you against one you already have.

Like for viruses that have a vaccine, normally you wouldn’t vaccinate someone who had the virus already because the vaccine would be redundant - they already have natural immunity.

But in the case of HPV, apparently they don’t have effective natural immunity, the immunity naturally acquired is worse than the vaccine one. So why can’t the vaccine one take effect after the absent (or at least ineffective one) natural one isn’t (or is slightly) in place? That’s what I don’t understand. It seems like the natural immunity prevents the vaccine induced immunity from developing, but the natural immunity in this case doesn’t seem to work, while the vaccine induced immunity does work. Why…?