Figure 1.

PRISMA flowchart for study selection. * Reasons for exclusion; (P) population: NIC I patients, patients with immunosuppression associated with HPV, pathologies associated with HPV other than cervical intraepithelial, studies with male subjects, and studies with animals; (I) intervention: vaccination program or prophylactic vaccine; (S) study design: reviews, specialist opinions, theses, dissertations, and observational studies. ** RCT = Randomized Controlled Trial; NCRT = Non-Randomized Controlled Trial.