Two ongoing vaccine trials in Africa (the Kenya single-dose HPV-vaccine efficacy [KEN SHE] trial, which focused on HPV infection prevention in sexually active young women aged 15–20 in Kenya, and the Dose Reduction Immunobridging and Safety Study [DoRIS] trial, which focused on vaccine-mediated immune responses in girls aged 9–14 in Tanzania) provided the strongest and most compelling evidence for the WHO recommendation of a single-dose regimen.
In the KEN SHE trial, single-dose bivalent and nonavalent HPV vaccines showed 97.5% vaccine efficacy against persistent HPV16/18 infection at 18 months among women aged 15-20. Similar to multidose regimens, single-dose schedules of both HPV vaccines were highly effective in preventing incident persistent oncogenic HPV infection.
In the DoRIS trial, a single dose of the 2-valent or 9-valent HPV vaccine (Cervarix or Gardasil-9) in girls aged 9-14 induced robust immune responses up to 24 months, suggesting that this reduced dose regimen could be suitable for preventing HPV infection among girls in the target age group for vaccination.
Besides, a newly published immunobridging analysis compared HPV 16 and HPV 18 antibody responses after one dose of the HPV vaccine in the DoRIS trial with those in the KEN SHE trial. The immune responses at 24 months in girls aged 9–14 years were found to be non-inferior to those in young women aged 15–20 years from the KEN SHE trial and in whom efficacy had been shown up to 36 months following vaccine administration. This study also showed that antibody levels among girls receiving one dose of Gardasil-9 or Cervarix were at least as high as those in women from two historical cohorts (the CVT and the IARC India HPV trials).
Recommended resources:
1) Comparing one dose of HPV vaccine in girls aged 9-14 years in Tanzania (DoRIS) with one dose in young women aged 15-20 years in Kenya (KEN SHE): an immunobridging analysis of randomised controlled trials.
DOI: 10.1016/S2214-109X(23)00586-7
2) A dose-reduction HPV vaccine immunobridging trial of two HPV vaccines among adolescent girls in Tanzania (the DoRIS trial) – Study protocol for a randomised controlled trial.
DOI:10.1016/j.cct.2021.106266
3) Immunogenicity and safety of one-dose human papillomavirus vaccine compared with two or three doses in Tanzanian girls (DoRIS): an open-label, randomised, non-inferiority trial
DOI: 10.1016/S2214-109X(22)00309-6
4) Efficacy of Single-Dose Human Papillomavirus Vaccination among Young African Women
DOI:10.1056/EVIDoa2100056
5) Impact of one and two human papillomavirus (HPV) vaccine doses on community-level HPV prevalence in South African adolescent girls: study protocol and rationale for a pragmatic before-after design
DOI: 10.1136/bmjopen-2021-059968
6) Single dose HPV vaccine in achieving global cervical cancer elimination
DOI: 10.1016/S2214-109X(24)00009-3
7) Vaccine efficacy against persistent human papillomavirus (HPV) 16/18 infection at 10 years after one, two, and three doses of quadrivalent HPV vaccine in girls in India: a multicentre, prospective, cohort study
DOI:10.1016/S1470-2045(21)00453-8
