Vaccine tolerability was assessed as a primary objective. Safety and tolerability were assessed by clinical review of the following parameters: overall and vaccine-related injection- site (Days 1–5) and systemic adverse events (AEs; Days 1–15), as reported on VRCs, serious AEs (SAEs; Days 1–15), vaccine-related SAEs (throughout the study), and new medical conditions (throughout the study). The specific events of interest were injection-site AEs prompted for on the VRC, such as pain/tenderness, swelling, and erythema occurring from Days 1–5 following any vaccination; and elevated temperature (≥37.5°C) from Days 1–5 following any vaccination.Vaccination and follow-up: The qHPV vaccine was administered as 0.5-mL intramuscular injections at Day 1, Month 2, and Month 6, and each dose contained HPV6/11/16/18 L1 VLP 20/40/40/20 μg, respectively, and 225 μg aluminium hydroxyphosphate sulfate adjuvant. All participants were observed for at least 30 minutes after each vaccination for any untoward effects, including allergic reactions. Immunogenicity was assessed at Day 1 and Month 7. The qHPV cLIA was the primary assay used for the primary and secondary endpoints of the trial. For each visit that required a serum specimen for anti-HPV measurements, a 10-mL, non-heparinized, non-serum separator, red-top–tube blood specimen was collected and separated to avoid hemolysis.Statistical analyses: The per-protocol immunogenicity (PPI) population was the primary population for the analysis of immune response to HPV6/11/16/18. To be included, participants were required to have received all three vaccinations with the correct dose of the correct clinical material, with each vaccination visit occurring within acceptable day ranges. Participants must have provided a Month 7 serology result within 21–49 days post-Dose 38