Why we approved R21 malaria vaccine: WHO

The World Health Organization (WHO) on Monday recommended a new vaccine, R21, for the prevention of malaria in children.

It is the second malaria vaccine approved by WHO, following the approval of RTS,S. Nigeria approved the R21 vaccine in April, becoming the second country after Ghana to do so.

The global body said its recommendation was informed by the results of the WHO-coordinated Malaria Vaccine Implementation Programme, through which nearly 2 million children in Ghana, Kenya and Malawi have been reached with the RTSS/AS01 malaria vaccine since 2019.

The pilot introduction of the first malaria vaccine has resulted in a substantial impact in reducing severe malaria illness, hospitalizations and child deaths.

Developed by Oxford University and manufactured by the Serum Institute of India, R21, also known as Matrix-M, showed 80% protection in early trials and has been described as a “world-changer” by the scientists who developed it.

Key features of the R21 malaria vaccine: 

WHO said its updated malaria vaccine recommendation is informed by evidence from an ongoing R21 vaccine clinical trial and other studies, which showed:

• High efficacy when given just before the high transmission season: In areas with highly seasonal malaria transmission (where malaria transmission is largely limited to 4 or 5 months per year), the R21 vaccine was shown to reduce symptomatic cases of malaria by 75% during the 12 months following a 3-dose series. A fourth dose given a year after the third maintained efficacy. This high efficacy is similar to the efficacy demonstrated when RTS,S is given seasonally.
• Good efficacy when given in an age-based schedule:  The vaccine showed good efficacy (66%) during the 12 months following the first 3 doses. A fourth dose a year after the third maintained efficacy.
• High impact: Mathematical modelling estimates indicate the public health impact of the R21 vaccine is expected to be high in a wide range of malaria transmission settings, including low transmission settings.
• Cost effectiveness: At prices of US$ 2 – US$ 4 per dose, the cost-effectiveness of the R21 vaccine would be comparable with other recommended malaria interventions and other childhood vaccines.
• Similarity of R21 and RTS,S vaccines: The two WHO-recommended vaccines, R21 and RTS,S, have not been tested in a head-to-head trial. There is no evidence to date showing one vaccine performs better than the other. The choice of product to be used in a country should be based on programmatic characteristics, vaccine supply, and vaccine affordability
• Safety: The R21 vaccine was shown to be safe in clinical trials. As with other new vaccines, safety monitoring will continue.

Next steps for the second recommended malaria vaccine, R21/Matrix-M, include completing the ongoing WHO prequalification which would enable international procurement of the vaccine for broader rollout.

At least 28 countries in Africa plan to introduce a WHO-recommended malaria vaccine as part of their national immunization programmes. Gavi, the Vaccine Alliance has approved providing technical and financial support to roll out malaria vaccines to 18 countries. The RTS,S vaccine will be rolled out in some African countries in early 2024, and the R21 malaria vaccine is expected to become available to countries mid-2024.