Immunogenicity of 9-valent HPV Vaccine

All participants will receive the immunization schedule according to guidelines: immunosuppressed patients will receive a three-dose schedule: 0.5 mL intramuscular injection of 9vHPV at entry plus an additional dose at month 2 and month 6. Healthy controls aged 9-14 years will receive a two-dose schedule: 0 and 6 months.