There are currently three licensed and WHO pre-qualified HPV vaccines available globally. Although Gavi-subsidized for the poorest countries, they remain out of reach for many low-and middle-income countries who do not benefit from Gavi support or are transitioning out Gavi. Novel approaches to HPV vaccine with reduced dose schedules are being studied, but comparative data across studies is difficult to interpret due to differences in assays, timepoints tested, age-groups studied, and geographic settings for the studies.
At the request of Peter Dull, Deputy Director of the Integrated Clinical Vaccine Development team at the Bill & Melinda Gates Foundation, the START Center conducted a systematic literature review and meta-analysis to identify studies of any of the three licensed HPV vaccines that report post-vaccine immunogenicity data. Identified studies included those which used standard (i.e. WHO-approved) HPV vaccine dosing schedules as well as those which used either extended interval schedules (i.e. ≥12 months between first and second dose) or single-dose schedules. Prior to completion of the systematic review and meta-analysis, studies with extended interval or single-dose schedules were summarized in a slide deck and presented by PATH at the June 2019 WHO SAGE working group meeting. After completion of the systematic review, a meta-analysis was conducted to compare the immunogenicity of extended interval/single-dose schedules to that of the standard dose schedules for each licensed vaccine. A report detailing the results of the systematic review and meta-analysis was compiled and will be used to inform HPV vaccine investment decisions at the Bill & Melinda Gates Foundation.