Antibodies to HPV Types 6, 11, 16, and 18 were measured using a competitive luminex immunoassay 4 weeks after 3rd vaccination (Month 7). Antibody titers were expressed as milli Merck units/mL (mMU/mL). Seroconversion was defined as an anti-HPV 6 titer ≥20 mMU/mL, an anti-HPV 11 titer ≥16 mMU/mL, an anti-HPV 16 titer of ≥20 mMU/mL and an anti-HPV 18 titer of ≥24 mMU/mL.

The parent/guardian of the participant was to record the participant's oral temperature in the evening after each study vaccination and daily for 4 days after each study vaccination. Elevated temperature was defined as ≥99.5°F (≥37.5ºC). The percentage of participants that had an elevated temperature was summarized.

An adverse event (AE) is defined as any untoward medical occurrence in a participant which does not necessarily have a causal relationship with study drug. An AE can therefore be any unfavourable and unintended sign, symptom, or disease temporally associated with the use of study drug or a protocol-specified procedure, whether or not considered related to the study drug or protocol-specified procedure. Any worsening of a preexisting condition that is temporally associated with the study drug or protocol-specified procedure is also an AE. The parent/guardian of the participant was to record the presence of any vaccination report card (VRC)-prompted injection-site AEs that occurred in the 5 days after any vaccination. The percentage of participants with an injection-site AE prompted on the VRC (erythema, pain, and swelling) was summarized.

An adverse event (AE) is defined as any untoward medical occurrence in a participant which does not necessarily have a causal relationship with study drug. An AE can therefore be any unfavourable and unintended sign, symptom, or disease temporally associated with the use of study drug or a protocol-specified procedure, whether or not considered related to the study drug or protocol-specified procedure. Any worsening of a preexisting condition that is temporally associated with the study drug or protocol-specified procedure is also an AE. The parent/guardian of the participant was to record the presence of any VRC-prompted systemic AEs that occurred in the 5 days after any vaccination. The percentage of participants with a systemic AE was summarized.

An AE is defined as any unfavorable and unintended change in the structure, function, or chemistry of the body temporally associated with the use of the sponsor's product, whether or not considered related to the use of the product. A serious adverse event (SAE) is an AE that results in death, is life threatening, results in a persistent or significant disability or incapacity, results in or prolongs an existing hospitalization, is a congenital anomaly or birth defect, is a cancer, is an overdose, or is another important medical event. The percentage of participants that experienced 1 or more SAEs was summarized.

An AE is defined as any unfavorable and unintended change in the structure, function, or chemistry of the body temporally associated with the use of the sponsor's product, whether or not considered related to the use of the product. A serious adverse event (SAE) is an AE that results in death, is life threatening, results in a persistent or significant disability or incapacity, results in or prolongs an existing hospitalization, is a congenital anomaly or birth defect, is a cancer, is an overdose, or is another important medical event. The percentage of participants that experienced 1 or more SAEs that were considered at least possibly related to the study vaccine was summarized.

Persistent infection was defined as 1) polymerase chain reaction (PCR) positive to HPV Type 6, 11, 16, or 18 in 2 consecutive anogenital or biopsy samples collected ≥4 months apart, or 2) Pathology Panel consensus diagnosis of condyloma acuminate, penile/perianal/perineal intraepithelial neoplasia (PIN), penile, perianal, or perineal cancer and PCR detection of HPV Type 6, 11, 16, or 18 in an adjacent section and PCR positive for the same HPV type at a separate adjacent visit. The combined incidence of HPV Type 6, 11, 16, or 18 persistent infection detected in samples from ≥2 consecutive visits ≥6 months apart was assessed.

Body temperature (oral or oral equivalent) was recorded on the Vaccination Report Card (VRC). The percentage of participants with a maximum temperature ≥37.5°C was summarized.

An adverse event (AE) is defined as any untoward medical occurrence in a participant which does not necessarily have a causal relationship with study drug. An AE can therefore be any unfavourable and unintended sign, symptom, or disease temporally associated with the use of study drug or a protocol-specified procedure, whether or not considered related to the study drug or protocol-specified procedure. Any worsening of a preexisting condition that is temporally associated with the study drug or protocol-specified procedure is also an AE. The percentage of participants with an injection-site AE prompted on the VRC (erythema, pain, and swelling) was summarized.

An adverse event (AE) is defined as any untoward medical occurrence in a participant which does not necessarily have a causal relationship with study drug. An AE can therefore be any unfavourable and unintended sign, symptom, or disease temporally associated with the use of study drug or a protocol-specified procedure, whether or not considered related to the study drug or protocol-specified procedure. Any worsening of a preexisting condition that is temporally associated with the study drug or protocol-specified procedure is also an AE. Vaccine-related AEs are those that were deemed possibly, probably, or definitely related to vaccine administration by the investigator. The percentage of participants with a vaccine-related systemic AE was summarized.