RH5.1/Matrix-MTM Blood-Stage Malaria Vaccine Dosage, Indication, Side Effects
The University of Oxford studies the RH5.1/Matrix-M blood-stage malaria vaccine candidate in children and adults. Unlike the previously approved malaria vaccines that target the liver-invasive sporozoite, which can infect the liver with a risk of clinical disease, RH5.1/Matrix-M targets the pre-erythrocyte stage.
The results of the phase 2b clinical trial by Natama and colleagues indicated that RH5.1/Matrix-M had a vaccine efficacy of 55% (95% CI 20 to 75; p=0·0071) compared with the control group when administered at 0, 1, and 5-month intervals, and 40% (–3 to 65; p=0·066) on a monthly regimen (0, 1, and 2 months). The authors indicated the vaccine was well tolerated, with only mild adverse events (fever and injection site swelling). Moreover, participants vaccinated with RH5.1/Matrix-M showed high concentrations of anti-RH5.1 serum IgG antibodies and high levels of in-vitro growth inhibition activity against Plasmodium falciparum.
On January 7, 2025, the authors of a Commentary published by The Lancet Infectious Diseases stated, 'This blood-stage candidate vaccine RH5.1/Matrix-M will complement the previously WHO-recommended and rolled out pre-erythrocyte malaria vaccines (RTS,S/AS01, and R21/Matrix-M) for effective and durable protection, targeting different stages of the parasite life cycle.'
RH5.1/Matrix-MTM Blood-stage Malaria Vaccine Dosage
In phase 2b, the vaccine was administered at 0, 1, and 5-month intervals and as part of a monthly regimen (0, 1, and 2 months).
RH5.1/Matrix-MTM Blood-stage Malaria Vaccine Indication
The WHO reported around 263 million malaria cases in 2023 and 597,000 related fatalities. Plasmodium falciparum parasites cause malaria. Blood-stage malaria, when the parasite infects red blood cells, causes symptoms of the disease like fever and chills and can lead to severe, life-threatening complications like anemia and organ failure.
RH5.1/Matrix-MTM Blood-stage Malaria Vaccine Side Effects
Most adverse events in the phase 2b study were mild, with local swelling and fever being the most common. No serious adverse events were reported.
RH5.1/Matrix-MTM Blood-stage Malaria Vaccine News
December 10, 2024 - Trial results for the first vaccine against blood-stage malaria show that it is well-tolerated and offers effective protection.
June 13, 2024 - Blood-stage malaria vaccine candidate RH5.1/Matrix-M in healthy Tanzanian adults and children; an open-label, non-randomized, first-in-human, single-center, phase 1b trial.
RH5.1/Matrix-MTM Blood-stage Malaria Vaccine Clinical Trials
The phase 2b study team tested the safety and efficacy of the RH5.1/Matrix-MTM blood-stage malaria vaccine candidate in adults and children aged 5 to 17 months in Nanoro Burkina Faso, following positive phase one results in Tanzanian adults and children. Over 360 children were enrolled in the study in 2023 and divided into two groups: one received three doses of the RH5.1/Matrix-MTM and the other three doses of a rabies vaccine as control.
Children who received the vaccine developed high levels of antibodies against the parasite, especially those who received their vaccine doses at 0, 1, and 5 months rather than at 0, 1, and 2 months. This group achieved 55% effectiveness in preventing clinical malaria over 6 months. Alongside this, within the group of children who did develop clinical malaria, a proportion showed very high levels of parasites in their blood. Notably, the vaccine also demonstrated over 80% efficacy against these higher levels of malaria parasites, suggesting this vaccine could prevent severe cases of the disease in children in a real-world setting. These findings will now be explored further in future clinical trials.
The study has been run by scientists at the University of Oxford in collaboration with the Clinical Research Unit of Nanoro at the Institut de Recherche en Sciences de la Santé in Burkina Faso, the London School of Hygiene and Tropical Medicine, and the U.S. National Institute of Health, with support from other partners including the Serum Institute of India Pvt. Ltd, Novavax, and ExpreS2ion Biotechnologies ApS.
Phase 1b clinical trial - Blood-stage malaria vaccine candidate RH5.1/Matrix-M in healthy Tanzanian adults and children; an open-label, non-randomized, first-in-human, single-center. Interpretation: The RH5.1/Matrix-M vaccine candidate shows an acceptable safety and reactogenicity profile in both adults and 5–17-month-old children residing in a malaria-endemic area, with all children in the delayed third dose regimen reaching a level of GIA previously associated with protective outcome against blood-stage P falciparum challenge in non-human primates. These data support the onward efficacy assessment of this vaccine candidate against clinical malaria in young African children.
