Last Updated: 02/12/2024

Safety and immunogenicity evaluation of the malaria vaccine, RTS,S/AS01, in healthy Thai adults

Objectives

To test, in Thai adults, safety and immunogenicity of RTS,S/AS01 administered in conjunction with anti-malarial drugs. If results are promising, it will form the basis for assessing the impact of RTS,S/AS01 vaccination in targeted malaria elimination programs in the Greater Mekong Subregion.

Principal Investigators / Focal Persons

Lorenz Von Seidlein

Rationale and Abstract

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.

Study Design

Study Type: Interventional (Clinical trial)

Allocation: Randomized

Intervention Model: Parallel Assignment

Intervention Model Description: Randomized 7 groups

Masking: None (open label)

Primary purpose: prevention

Date

Dec 2016 — Feb 2018

Country / Project Site(s)

Thailand

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