What is the new Malaria vaccine (R21/Matrix-M)?

The R21/Matrix-M vaccine is the latest malaria vaccine to be recommended by the World Health Organization (WHO) to protect children from malaria in at-risk countries. It targets the first form of the malaria parasite (the plasmodium sporozoite) to enter the body after a person is bitten by an infected mosquito. Now there are two anti-malaria vaccines that can be used to protect children. The other vaccine, RTS,S/AS01 (Mosquirix) was previously recommended by the WHO in 2021.

The demand for the first malaria vaccine, RTS,S/AS01, has consistently exceeded the available supply. The introduction of this second vaccine, R21/Matrix-M, is expected to address this supply-demand gap and ensure that more children residing in regions where malaria poses a significant public health threat can access the vaccine. Malaria is a mosquito-borne disease that disproportionately affects children in the African Region, where nearly half a million children die from the disease annually.

The new malaria vaccine R21/Matrix-M was developed by the University of Oxford and the Serum Institute of India.

How does the new malaria vaccine, R21/Matrix-M, work?

The R21/Matrix-M vaccine focuses on the plasmodium sporozoite, the initial stage of the malaria parasite upon entering the human body. When an anopheles mosquito carrying the malaria parasite bites a person, it introduces the parasite into the bloodstream, where it undergoes various transformations in its life cycle. The complexity of this life cycle has posed challenges for malaria vaccine development over the years.

The R21/Matrix-M vaccine specifically targets the plasmodium 'sporozoite,' which is the earliest form of the malaria parasite upon entering the human host. During the mosquito's bite, only a small number (10–100) of sporozoites are injected before the parasite begins to multiply. This makes sporozoites an ideal target for a vaccine.

R21 is categorized as a subunit vaccine, delivering components of a protein secreted by the sporozoite. These components are combined with a segment of the hepatitis B virus known to elicit a robust immune response.

How effective is the R21 Malaria vaccine?

In regions where malaria transmission is highly seasonal, occurring primarily for 4 or 5 months each year, the R21 vaccine has displayed significant effectiveness. It was found to reduce symptomatic malaria cases by 75% in the year following a 3-dose series. Furthermore, the sustained efficacy of the vaccine was maintained with a fourth dose administered a year after the third. This high level of effectiveness is comparable to the efficacy demonstrated when using the RTS,S vaccine seasonally.

Additionally, when the R21 vaccine is administered based on age, it still demonstrates substantial efficacy, with a 66% reduction in malaria cases during the year following the first 3 doses. Again, a fourth dose given a year after the third dose maintains this efficacy.

Which vaccine Is more effective: R21/Matrix-M or RTS,S (Mosquirix)?

The WHO-recommended vaccines, R21 and RTS,S, have not been directly compared in a head-to-head trial. As of now, there is no conclusive evidence to suggest that one vaccine outperforms the other. The decision on which vaccine to use in a particular country should be guided by programmatic factors, vaccine availability, and cost-effectiveness considerations.

Is the new Malaria vaccine approved in the U.S.?

No, R21/Matrix-M has not been approved in the U.S., but it has been licensed for use in Ghana, Nigeria, and Burkina Faso.

What is Malaria?

Malaria is a severe and sometimes deadly illness caused by a parasite commonly transmitted through certain types of mosquitoes that bite humans. People who contract malaria often experience high fevers, intense chills, and symptoms resembling the flu. Four main types of malaria parasites affect humans: Plasmodium falciparum, P. vivax, P. ovale, and P. malariae.

Unfortunately, between 2019 and 2020, there was a 6% increase in malaria cases and a 12% rise in deaths globally, despite efforts to maintain essential malaria services during the COVID-19 pandemic. Most of these cases occurred in the WHO African region, and a staggering 80% of malaria-related deaths were among children under 5 years old. The 2020 goals set by the WHO Global Technical Strategy for Malaria 2016–2030 were not met, with approximately 640,000 malaria deaths reported in 2020. There is hope that the broader use of the RTS,S/AS01 (Mosquirix; GlaxoSmithKline) malaria vaccine as well as the new R21/Matrix-M malaria vaccine will reinvigorate efforts in the battle against malaria.