A Longitudinal Observational Cohort Study to Assess Sustained Immunogenicity up to 48 Months to Quadrivalent Human Papillomavirus Vaccine Among HIV-infected Girls and Boys Age 9-14 Years in Kenya

HIV-infected individuals bear a disproportionate disease burden of HPV-related diseases suggesting more rapid progression from HPV acquisition to malignancy. HIV infected women have a 2-22 fold increased risk for cervical cancer compared to uninfected women. The quadrivalent HPV vaccine marketed as "Gardasil" has demonstrated efficacy against type specific HPV infections known to cause 70% cervical cancer (HPV 16 & 18) and HPV 6 & 11 known to cause 90% of anogenital warts in populations of HIV negative young women.

Since the risk of HPV exposure persists throughout a person's sexual life, the duration of protection, especially when the vaccine is given in the pre-adolescent period, is critical to overall vaccine effectiveness. Extended follow up of HIV-uninfected individuals has shown sustained response to HPV vaccine for 8.4 and 6 years respectively to the bivalent and quadrivalent vaccines. However, other vaccines such as the hepatitis B vaccine have been shown to require additional dosages to be effective among HIV-infected persons.

Data on immunogenicity of the HPV vaccine among HIV infected adolescents is limited to a 12 month follow up period.

Current HPV vaccine guidelines target pre-sexual adolescents. Since the risk of HPV exposure persists throughout an individual's sexual life, the duration of protection provided by vaccination is critical to the overall vaccine effectiveness. Duration of sustained HPV 6/11/16/18 antibody response is directly related to vaccine effectiveness and determines the need for booster dosing.

The investigators therefore propose to extend follow up of 179 girls and boys in Kenya, age 9-14 years who have received 3 doses of the quadrivalent 'Gardasil' vaccine and assess for immunogenicity annually.