Immunogenicity of Bivalent HPV Vaccine Among Partially Vaccinated Young Adolescent Girls in Uganda
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
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.
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.
Girls who received at least one dose of the HPV vaccine, 12-20 years of old, in apparent
good general health.
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.
Time Perspective: Prospective
Mahboobeh Safaeian, M.D.
National Cancer Institute (NCI)
United States: Federal Government