Malaria vaccines RTS,S and R21 protect children against the most dangerous malaria parasite. Learn how they work and where they are used.
What Are Malaria Vaccines?
Malaria is a serious disease caused by parasites that are spread to people through the bites of infected mosquitoes. The World Health Organization states that malaria causes around 250 million infections and 600 000 deaths each year across the world, with young children in Africa among the most affected. Vaccines are a vital tool to prevent this disease. The RTS,S and R21 vaccines are the first to be recommended by the WHO for use in children. They target Plasmodium falciparum, the deadliest malaria parasite globally. Both vaccines train the immune system to recognise and fight this parasite. They offer a new way to protect children who live in areas where malaria is common, reducing the risk of severe illness and death.
How Do the Vaccines Work?
The RTS,S and R21 vaccines act against the Plasmodium falciparum parasite, as confirmed by the World Health Organization. The European Medicines Agency explains that the active substance in one of these vaccines is made from proteins found on the surface of the parasite and the hepatitis B virus. When a person receives the vaccine, their immune system makes antibodies against these proteins. These antibodies then attack the parasite if it enters the blood through a mosquito bite. The vaccines limit the ability of the parasite to mature in the liver and cause clinical disease. This means that vaccinated children are less likely to develop malaria symptoms, and if they do, the illness is often less severe.
Who Should Receive the Vaccines?
The World Health Organization recommends both RTS,S and R21 for children living in areas where malaria is a public health risk. The vaccines are given to children from around 5 months of age, with a schedule of four doses. A fifth dose may be considered one year after the fourth in areas of highly seasonal transmission. The vaccines are not currently recommended for travellers or adults, as they are intended for routine immunisation in malaria-endemic countries. It is important to follow the official recommendations in each area, as stated by the European Medicines Agency. These vaccines are a major step forward in child health, offering protection to the most vulnerable populations. Both vaccines arrive in a four-dose schedule, with a fifth dose possible in highly seasonal areas.
How Effective Are They?
Clinical trials have shown that the RTS,S and R21 vaccines are effective in reducing malaria cases. The World Health Organization reports that in phase 3 trials, both vaccines reduced malaria cases by more than 50% during the first year after vaccination. When given seasonally in areas with highly seasonal transmission, they prevented around 75% of malaria episodes. A fourth dose given a year after the third helps maintain the protection. In a pilot programme with over 2 million children, there was a 13% drop in deaths among age-eligible children. The vaccines are not 100% effective, but they provide significant protection and can save many lives when used alongside other measures. The R21 vaccine maintained efficacy when a fourth dose followed the first three by a year.
Where Are the Vaccines Being Used?
As of 4 February 2026, 25 countries in Africa are offering malaria vaccines, according to the World Health Organization. These countries target more than 10 million children per year. The RTS,S vaccine was first recommended by WHO in October 2021, and R21 followed in October 2023. The R21 vaccine is now available and is expected to help meet the high demand for malaria vaccines. The addition of R21 is anticipated to ensure sufficient supply for all children living in areas where malaria is a public health risk. The vaccines are delivered through routine immunisation programmes and are also used in seasonal campaigns in regions with highly seasonal transmission. R21 became available to countries by mid-2024, helping meet the high demand for vaccines.
What Is the Safety Profile?
The World Health Organization describes both vaccines as safe and efficacious. Clinical trials and pilot programmes have monitored their safety. The European Medicines Agency reports that in a study of over 12,000 children, the most serious side effect was febrile seizures, which occurred in about 1 in 1,000 children. Fever was seen in about 1 in 4 children. These side effects are generally temporary and manageable. The benefits of vaccination far outweigh the risks in areas where malaria is a major health problem. The vaccines have been prequalified by WHO, meaning they meet international standards for quality, safety and efficacy, and they continue to be monitored after rollout. Febrile seizures and fever are reported side effects, but serious effects stay rare.
A Step Forward in Malaria Control
The introduction of effective malaria vaccines marks a major milestone in public health. They are a new tool to complement existing measures such as bed nets and preventive drugs. The World Health Organization stresses that vaccines should be used alongside other malaria control strategies. For the public, these vaccines offer hope for reducing the heavy burden of malaria. They have the potential to save thousands of young lives each year. Research and vaccination programmes continue, and with growing supply and lower costs, more children can be protected. This progress is the result of global cooperation and represents a significant achievement in the fight against malaria. Malaria vaccines are not 100 per cent effective, yet they significantly reduce severe illness and death.
Sources
- Malaria vaccines (RTS,S and R21): World Health Organization
- WHO recommends R21/Matrix-M vaccine for malaria prevention in updated advice on immunization: World Health Organization
- Mosquirix - opinion on medicine for use outside EU: European Medicines Agency
- Disease information about malaria: European Centre for Disease Prevention and Control