Paving the Way to a Malaria-Free World with Malaria Vaccines

Malaria is one of the major public health problems globally. Among all communicable diseases, malaria is the third leading cause of death in children aged one month to five years, following pneumonia and diarrhea. The disease continues to affect millions, particularly in tropical and subtropical regions, where the highest rate of infection and death occur.

Given the high prevalence and mortality rate of malaria, the need for more effective solutions has never been greater. While preventive measures like insecticide-treated bed nets and antimalarial drugs do help, the disease continues to be a major threat due to its complexity and evolving resistance to treatments. Vaccination has emerged as a promising tool in the fight against malaria, offering the potential for long-term protection.

With major advancements in malaria vaccine development, could the disease finally be on the brink of defeat? In this blog, we explain to you the basics of malaria and how it’s caused. Also, we cover the crucial role of malaria vaccines and the ones recommended by the World Health Organization (WHO). Read on!

Malaria: Quick Overview

Malaria is a potentially life-threatening infectious disease spread to humans by some types of mosquitoes. It is caused by the bites of infected female Anopheles mosquitoes. There are five species of the Plasmodium parasite that lead to malaria in humans. And two of these species, P. falciparum and P. vivax,  present the biggest threat. P. falciparum is the most virulent cause of malaria in humans and is highly prevalent on the African continent. P. vivax is a highly dominant malaria parasite in most countries outside of sub-Saharan Africa. Other malaria species that can infect humans include P. knowlesi, P. ovale, and P. malariae.

Significance of World Malaria Day

World Malaria Day is celebrated annually on April 25 to raise awareness about malaria, its control, prevention, and ongoing efforts to eradicate it. It aims to highlight the global burden of malaria and serves as a reminder of the importance of continued investment in research and implementation of prevention strategies. The day also honors the progress made in reducing malaria-related deaths and infections globally.

WHO introduced the World Malaria Day in 2007. Since then, the WHO has designated a theme for it to focus attention on particular aspects of malaria control, progress, and the need for continuous efforts to eliminate the disease globally.

How Do Malaria Vaccines Help Prevent Infection?

Malaria vaccines are designed to prevent infection by the Plasmodium parasites. These vaccines stimulate the immune system to recognize and fight the parasites before they lead to severe illness or death. Here’s how these vaccines work:

Priming the Immune System: Malaria vaccines contain proteins for the malaria parasite, such as the RTS,S protein. These proteins prime the immune system to recognize the parasite when encountered in the future.

Immunizing Against Liver Stages: After a mosquito bite, the parasite first makes its way to the liver before infecting red blood cells. The vaccine focuses on preventing the parasite from completing its development in the liver, which is crucial for the spread of the disease.

Prevention of Severe Malaria: By offering immunity to the liver stage of the parasite’s life cycle, the vaccine reduces the chances of the parasite reaching the bloodstream. This helps reduce the severity and frequency of malaria infections.

WHO-Recommended Malaria Vaccines Explained

As of now, the WHO recommends two malaria vaccines for use, especially in high-risk regions. These are:

RTS,S/AS01 (Mosquirix)

• Developer: GlaxoSmithKline (GSK) in collaboration with PATH
• Recommendation: In October 2021, the WHO recommended the RTS,S/AS01 for widespread use in children aged 6 months to 5 years in regions with moderate to high transmission of Plasmodium falciparum malaria. In October 2022, WHO granted prequalification to GlaxoSmithKline’s RTS,S/AS01 vaccine.
• How It Works: This vaccine focuses on the Plasmodium falciparum parasite’s liver stage. It introduces a protein found on the parasite's surface, stimulating the immune system to develop defenses against malaria.
• Effectiveness: The vaccine doesn’t offer complete immunity, but it significantly reduces malaria-related illness and death. The effectiveness varies among patients and regions but studies have shown a reduction in cases by about 30-40% over the long term.

R21/Matrix-M

• Developer: University of Oxford and Serum Institute of India
• Recommendation: In April 2021, the R21/Matrix-M vaccine received positive recommendations from the WHO for further use in the field. The vaccine was prequalified by WHO in December 2023, which is a prerequisite for vaccine procurement by organizations like UNICEF and funding support from Gavi, the Vaccine Alliance.
• How It Works: As with RTS,S, the R21/Matrix-M vaccine targets the Plasmodium falciparum parasite. It functions by inducing an immune response to proteins found on the surface of the parasite’s sporozoite stage, the stage transmitted by mosquitoes.
• Effectiveness: The R21/Matrix-M vaccine demonstrated an impressive 77% efficacy in clinical trials. This makes it one of the most effective malaria vaccines ever tested.
• Recent Development: In May 2024, the Serum Institute of India shipped its first set of R21/Matrix-M vaccine doses for distribution across the African region.

Malaria in Numbers: Key Statistics

According to data by the WHO, an estimated 2.2 billion cases of malaria and 12.7 million deaths have been prevented since 2000. However, the disease is still a significant global health concern, especially in the WHO African region, which has a disproportionately high share of global malaria cases.

The latest World Malaria report reveals that there were 263 million malaria cases and 597,000 malaria deaths globally in 2023. This represents a rise of about 11 million more cases than in 2022.

In 2023, the WHO African region witnessed 94% of all malaria cases and 95% of deaths. Children under the age of 5 represent about 76% of all malaria-related deaths in the region.

More than half of these deaths occurred in four countries: Nigeria (30.9%), the Democratic Republic of the Congo (11.3%), Niger (5.9%), and the United Republic of Tanzania (4.3%).

Malaria Vaccines: Way Forward

In conclusion, malaria remains a significant global health challenge. The development and deployment of vaccines offer a promising step toward reducing the burden of this deadly disease. With vaccines like RTS,S and R21/Matrix-M showing promising results, there is hope for a future where malaria can be controlled or even eradicated. Continued research, global collaboration, and equitable distribution are essential to ensuring that these vaccines reach those who need them most, paving the way for a malaria-free world.