Due to their immunosuppressive therapy, solid-organ transplant (SOT) recipients bear a 10 to 100 times higher risk of human papillomavirus (HPV)-associated malignancies than healthy individuals. The objectives of this observational, non-interventional multi-national, multi-centre research project are to gain an insight into current HPV vaccination strategies and to investigate the immune response to different routinely administered HPV vaccines in European paediatric SOT candidates and immunocompromised transplant recipients, enabling patients at risk of vaccination failure to be identified.

Inclusion Criteria:

• Paediatric Kidney and/or Liver transplant recipients
• Paediatric patients with CKD
• Who receive HPV vaccination according to country-specific vaccine schedule

Exclusion Criteria:

• No HPV vaccination according to country-specific vaccine schedule
• No written informed consent

Paediatric Kidney and/or Liver transplant recipients Paediatric patients with CKD