Completed Infection & Immunity NIHR-supported project Pregnancy, Children & Inherited Conditions

Phase I clinical trial to assess the safety and immunogenicity of the malaria vaccine candidate RH5.1 soluble protein in Matrix-MTM using two dosing regimens

Funder NIHR (part of DHSC)
Recipient organisation NIHR Oxford Biomedical Research Centre
NIHR support Recorded as supported by this research centre
Period Apr 2025 — Aug 2025

In plain English

AI plain-English summary

A malaria vaccine candidate is being tested in healthy volunteers to see if a simpler dosing schedule can trigger a strong immune response. The problem is that current malaria vaccine regimens are complex. One promising approach uses a "delayed fractional dose"—a small final dose given months after the initial shots—which boosts antibody production. But it is unclear whether the benefit comes from the long delay or the reduced dose itself. This trial separates those two factors. Volunteers receive either three standard 10-microgram doses or two 50-microgram doses followed by a delayed 10-microgram dose. Researchers will compare safety and immune responses between the groups. If the delay alone proves sufficient, vaccine developers could drop the fractional dose step. That would simplify manufacturing and national rollout programmes, making it easier to deliver a single, consistent dose schedule to millions of people at risk of malaria. The trial is a direct step toward a more practical vaccine, not fundamental science—success would mean a clearer path to a deployable product that saves lives in the field.

View original technical description
The vaccine we are testing in this study is called and RH5.1 . This is given with an adjuvant called Matrix-M . This is a substance to improve the body s response to a vaccination. The aim is to use the vaccines and adjuvant to help the body make an immune response against parts of the malaria parasite. This study will assess: 1. The safety of the vaccines in healthy participants. 2. The response of the human immune system to the vaccines. We will do this by giving participants three doses of the RH5.1 vaccines at two different dose levels (10 micrograms and 50 micrograms). One group will have 3 doses of 10micrograms given at 0,1 and 6 months whilst the other will receive 2 doses of 50micrograms (at 1 and 2 months) followed by a 10 microgram dose at 6 months- known as a 'delayed fractional dose'. We will then do blood tests and collect information about any symptoms that occur after vaccination. Information from previous studies suggests that a delayed fractional dose improves the immune response to the vaccine,particularly in terms of the antibody response. We suspect that this improvement is due to the delay in dosing,rather than the reduction in dose,and this study will help to answer that. Having a vaccine at a single dose is important for efficient production and dosing for vaccines rolled out in national programs so being able to move away from 'delayed fractional dose' regimens to 'delayed final dose' regimens will be important for vaccine development.

Researchers

Angela Minassian (Principal Investigator)

Related Research

Grants with similar aims, by meaning.

An open label Phase I/IIa clinical trial to assess the safety, immunogenicity and efficacy of the malaria vaccine candidate RH5.2-virus-like particle (VLP) in Matrix-MTM, and to compare the safety and immunogenicity of the malaria vaccine candidates RH5.2-VLP in Matrix-MTM and RH5.1 soluble protein in Matrix-MTM used in various regimens
A Phase Ia clinical trial to assess the safety and immunogenicity of the blood-stage malaria candidate vaccines RH5.1 in Matrix-MTM and R78C in Matrix-MTM, both alone and in combination, in healthy UK adults
MICA: Large-Scale Vaccine Fill and Phase I Clinical Trial of the RH5.1/Matrix-M Vaccine against Blood-Stage Plasmodium falciparum Malaria
Phase I clinical trial to assess the safety and immunogenicity of the malaria vaccine candidates RH5.2 virus-like particle (VLP) with Matrix-M, alone or together with RH5.1 soluble protein with Matrix-M
A phase 1 study to assess the safety and immunogenicity of R21/Matrix-MTM administered in an escalating dose, multi-prime vaccination schedule in healthy adults

Original classification

Life-saving Vaccines

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