A non-inferiority trial to assess the safety and immunogenicity of yellow fever vaccine dose sparing strategies for campaign and programmatic use
Medical Research Council
London School of Hygiene and Tropical Medicine
A phase 3, randomized, observer-blind non-inferiority trial will be undertaken to assess the safety and immunogenicity of fractional doses of the yellow fever vaccine when administered to 9-12 month olds in The Gambia. In 2016, the worst epidemic of yellow fever in 30 years occurred in Central Africa on a background of year on year increases in disease despite the availability of a safe and highly effective vaccine. A revised global strategy for epidemic elimination published by the WHO highlighted the critical role played by vaccine supply shortages in the current disease resurgence. These shortages became acute during the recent epidemic when, faced with the impending exhaustion of vaccine stockpiles, fractional (one fifth, 0.1mL) doses of the vaccine were recommended for ongoing emergency campaigns. This trial aims to generate a comprehensive data set on which to base future policy decisions regarding the use of fractional dose of the yellow fever vaccine in infants and children in sub-Saharan Africa. The following research questions will be addressed: 1. Does the administration of a fractional subcutaneous or intradermal dose of a yellow fever vaccine result in seroconversion rates which are non-inferior to those induced by a full subcutaneous dose of the same vaccine? 2. Is there a difference in the geometric mean antibody titres induced by fractional yellow fever vaccine doses according to whether administered by the subcutaneous or intradermal route? 3. Is there a difference in the safety profile of fractional yellow fever vaccine doses according to whether administered by the subcutaneous or intradermal route? Immunogenicity will be compared based on neutralizing antibodies. Local and systemic reactogenicity will be collected according to standard criteria. Other adverse events following immunization will also be recorded. The data are expected to influence future global vaccine policy decisions regarding fractional dose yellow fever vaccine use.
3.4 Vaccines / Research Grant