Safety and Immunogenicity Evaluation of the Malaria Vaccine, RTS,S/AS01, in Healthy Thai Adults

Detailed Summary

Targeted malaria elimination (TME), which comprises appropriate case management by village health workers, vector control and mass drug administration, is currently being implemented through pilot projects in selected villages in the Greater Mekong Subregion (GMS) and the scale-up of the intervention to the regional level are underway. Based on mathematical modelling, extending the post-TME parasitaemia-free period in the majority of villagers for as short as 200 days will substantially increase the chances of achieving the interruption of malaria transmission. Immunogenicity of RTS,S is greater in older children, and the short term malaria protective effect is stronger than the overall effect assessed over 1-2 years. Addition of mass RTS,S/AS01E vaccination to the TME arsenal could provide this much needed additional protection. Currently there are no safety and immunogenicity data for the use of RTS,S/AS01 in Asian populations. This trial will generate the required data for the use of this vaccine in Asian populations. For integration with the current TME activities, which provide mass drug administrations at months M0, M1, and M2, it would be most efficient and practical to provide the vaccine at the same intervals. To address a two round intervention (M0, M2) where a three round intervention is not feasible, one study arm will look at the immune response generated by only two doses of vaccine and antimalarial medications. Recent evidence suggests that a vaccination schedule which includes a fractional dose of RTS,S/AS01 (1/5th of the standard dose) could be similarly or more protective than a schedule with three standard full doses, while requiring less vaccine and resources. The trial therefore includes study arms which will assess the safety and immunogenicity of fractional dose schedules. Each participant will be randomized into one of the following study arms in a ratio of 20:20:30:30:30:30:30, as follows: * RTS,S/AS01B Fractional dose group (Group 1) * Double RTS,S /AS01E Fractional dose group (Group 2) * RTS,S/AS01E Standard dose group (Group 3) * RTS,S/AS01E + DHA-PIP+PQ Standard dose group (Group 4) * RTS,S/AS01E Fractional dose group (Group 5) * RTS,S/AS01E + DHA-PIP+PQ Fractional dose group (Group 6) * RTS,S/AS01E + DHA-PIP+PQ Fractional two-dose group (Group 7)

Study Details

Timeline

Interventions