Can the HPV vaccine be effective if you are already infected? [closed]

Question

I was just wondering about this subject, when I did a blood exam today and I picked a paper about available vaccines and I saw a vaccine against HPV, the same my mom always bothered me to take it.

I'm an adult man with active sexual life, so would I benefit from taking a HPV vaccine?

According to Wikipedia:

HPV is estimated to be the most common sexually transmitted infection in the United States.

The American Social Health Association reported estimates that about 75–80% of sexually active Americans will be infected with HPV at some point in their lifetime.

Answer 1

The HPV vaccine is most effective when preventing you from initial infection. While common, it's possible you haven't been infected with HPV. Even if you are, there is some benefit to still being vaccinated if you're HPV positive. The reason for this is that there are a number of different types of HPV virus, and the vaccine should provide you some protection against types you have not already acquired. From this MMWR report, "Human Papillomavirus Vaccination: Recommendations of the Advisory Committee on Immunization Practices":

In the phase III trials, among females aged 16–26 years who had HPV vaccine type DNA detected at study enrollment (either seropositive or seronegative), there was no efficacy against progression to disease or impact on clearance of infection of that type (114,120). However, HPV4 had 100% efficacy for prevention of CIN2+ attributable to types not already acquired (120). Among persons seropositive to the relevant HPV type but HPV DNA-negative, too few cases were detected to evaluate efficacy, but disease incidence was low and all cases occurred in the placebo group.

and

HPV vaccination can provide protection against infection with HPV vaccine types not already acquired. Therefore, vaccination is recommended through the recommended age for females regardless of whether they have an abnormal Pap test result, and for females or males regardless of known HPV infection, HPV-associated precancer lesions, or anogenital warts. Females who have abnormalities on cervical cancer screening are likely to be infected with one or more genital HPV types. With increasing severity of Pap test findings, the likelihood of infection with HPV 16 or HPV 18 increases (70), and the expected benefit of vaccination decreases. Females who have had HPV testing as part of cervical cancer screening might have information about their HPV status. Males or females with AIN are likely infected with HPV. The presence of anogenital warts or a history of anogenital warts indicates present or past infection with HPV, most often HPV 6 or HPV 11. Although vaccination is still recommended, patients should be advised that vaccination will not have any therapeutic effect on an existing HPV infection, HPV-associated precancer lesion, cancer, or anogenital warts.

In short: It is likely still worth getting vaccinated to protect you from other strains of HPV.