A Dose Reduction Immunobridging and Safety Study of Two HPV Vaccines in Tanzanian Girls
Status:
Active, not recruiting
Trial end date:
2024-03-01
Target enrollment:
Participant gender:
Summary
Cervical cancer is the most common cancer in women aged 15-44 years in East Africa, and
mortality rates are very high. HPV vaccines are most effective if given to girls who have not
yet acquired HPV infection. In Tanzania, HPV vaccine has been shown to be safe, acceptable
and can be delivered with high coverage (around 80%). However, the cost of delivering HPV
vaccine is considerably higher than costs for traditional infant/child vaccinations. This is
primarily because of costs to establish outreach programmes and associated personnel costs
including nurses who must spend significant time away from their posts to deliver vaccine,
especially if multiple doses are needed. There is global interest in simplifying HPV vaccine
delivery by reducing the number of doses. If a single dose could be given, this could halve
the costs of delivery, making it more accessible to the populations that need it most.
Recently, the WHO recommended that 2 doses of HPV vaccine could be given to young girls,
based on studies in high and upper middle income countries. However in Africa high rates of
infections like malaria and worms can affect immune responses to vaccines. It is essential to
know that reducing the number of doses does not reduce the protective immune response of
these vaccines. The investigators are conducting a trial in Tanzanian girls aged 9-14 years
to establish whether a single dose of HPV vaccine produces immune responses that are likely
to be effective in preventing cervical cancer. Two different HPV vaccines, the bivalent (2-v)
vaccine that protects against HPV 16/18 (the cause of 70% of cancers) and a new 9-valent
(9-v) vaccine that protects against 9 HPV types, will be compared. The trial will randomise
900 girls to 6 groups and follow them for 36 months. Girls will receive the 2-v or the 9-v
HPV vaccine, as 1, 2 or 3 doses. Girls receiving 1 or 2 doses will be compared with those
receiving 3 doses of the same vaccine, to ensure that the reduced dose regimen produces an
immune response that is not inferior to the standard 3 doses. The immune responses in this
study will also be compared with results from other countries where the vaccine has been
shown to be protective. This will provide information about whether a reduced number of doses
is likely to be protective in Africa. This work will be extremely important in informing
future HPV vaccination strategies and will be one of the first randomised trials of 1 and 2
doses of any HPV vaccine in Africa.
Phase:
Phase 3
Details
Lead Sponsor:
London School of Hygiene and Tropical Medicine
Collaborators:
Catalan Institute of Oncology Karolinska Institutet National Cancer Institute (NCI) Tanzanian National Institute for Medical Research Technische Universität Berlin University of Glasgow University of York