HPV Vaccine Effectiveness in Partially Vaccinated Girls in Uganda
Condition: HPV16 Anitbody Levels Post Vaccination; HPV18 Antibody Levels Post Vaccination
Study type: Observational

Summary: 
      Background:

      - Cervical cancer is one of the leading causes of cancer death in women worldwide and in
      Uganda. It is caused by the human papillomavirus (HPV). A vaccine against HPV was offered for
      all 10-year-old girls in the Nakasongola district of Uganda from October 1, 2008, to October
      31, 2009. The HPV vaccine requires three doses; however, some girls received only one or two
      doses. Researchers want to compare vaccine immunogenicity in girls who received all three
      doses with those who had only one or two doses.

      Objectives:

      - To examine the immunogenicity (antibody levels) of girls in Uganda who received only one,
      two or three doses of HPV vaccine.

      Eligibility:

        -  Girls who will be at least 12 years old by October 31, 2011, and had at least one dose
           of the HPV vaccine.

        -  All participants will come from the Nakasongola district of Uganda.

      Design:

        -  Participants will have a physical exam and answer questions about their medical history
           and HPV risk.

        -  Participants will provide a single blood sample for testing.

        -  Treatment and vaccines will not be provided as part of this study. Girls who did not
           receive all three doses of the HPV vaccine will be given information about the nearest
           health center. Health centers will provide the missed doses free of charge.
    

Detailed description: 
      Background:

      Recent experience with HPV vaccine implementation in low resource settings has suggested that
      high vaccine coverage for all three doses could be achieved provided programs are planned
      well and have full and complementary components in place. However, some locations experienced
      substantial rates of partially vaccinated girls, those who received only one or two doses.
      From the vaccine trial data published thus far, we know that the vaccines produce high levels
      of type-specific anti-HPV antibodies which begin to stabilize past 24 months
      post-vaccination. Without an immune correlate of protection, it is difficult to know whether
      girls who received one or two vaccine doses will still experience the same benefit of
      protection from HPV infection as those who received all three doses of vaccine.

      Recent data from a trial of a two-dose regimen of vaccination of girls aged 9-13 years in
      Vancouver, Canada have suggested that the immune response of girls who received only two
      doses was non-inferior both to that of girls who received 3 doses and to that of adult women
      aged 16-25 years who also received 3 doses. In a complementary study in Guanacaste, Costa
      Rica, vaccine efficacy (defined as 12-month vaccine type-specific infection persistence)
      among adult women who received either one or two doses of HPV vaccine as a part of the Phase
      IIb clinical trials of Cervarix (GSK) was similar to women who received all three vaccines
      doses.

      This proposed study would provide additional insight into the immunogenicity of HPV vaccine
      among partially vaccinated girls in Uganda, which could add supportive evidence in an African
      adolescent population (currently not represented in any clinical studies of HPV vaccines) of
      the immunological implications of receiving less than 3 doses of HPV vaccine.

      Objective:

      To investigate whether the anti-HPV 16 and/or anti-HPV-18 immune responses elicited by the
      bivalent vaccine for girls who received one dose and those who received two doses are similar
      at greater than or equal to 24 months (after last dose) to girls who received all three doses
      of bivalent HPV vaccine.

      Eligibility:

      Girls who received at least one dose of the HPV vaccine, 12-20 years of old, in apparent good
      general health.

      Design:

      This is a cross-sectional immunogenicity study with three groups:

      Group 1 - 200 girls who received only one dose of HPV vaccine as a part of the PATH-UNEPI HPV
      vaccine demonstration project;

      Group 2 - 200 girls who received only two doses of HPV vaccine as a part of the PATH-UNEPI

      HPV vaccine demonstration project; and

      Group 3 - 200 girls who received all three doses of HPV vaccine as a part of the PATH-UNEPI
      HPV vaccine demonstration project.

      This study will enroll girls (by group) within one district of Uganda from an HPV vaccine
      registry maintained by the district.

      Antibody level will be parameterized as the geometric mean titre of serum antibody to HPV
      types 16 and/or 18 at greater than or equal to 24 months after last dose of vaccine. Titres
      will be measured using the polyclonal Direct VLP ELISA.
    

Observational model: Cohort
Time perspective: Cross-Sectional
Keywords: HPV18 Immunogenicity; HPV16 Immunogenicity; Bivalent HPV16/18 Vaccine; Less than 3 Dosed of the Bivalent HPV Vaccine; HP Vaccine