Immunogenicity of Bivalent HPV Vaccine Among Partially Vaccinated Young Adolescent Girls in Uganda

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: