A Comprehensive Guide To The World’s First Malaria Vaccine

Malaria accounts for about 5% of all global deaths. WHO stated that about 67% of these deaths were children less than 5 years of age. Each year millions of malaria cases, predominantly in African countries. In these times, the malaria vaccine is a sought-after invention that is possible after decades of research. Please keep reading to learn about the vaccine’s development, how it works, and what it has achieved.

Life Cycle Of The Plasmodium falciparum

Knowledge of the malaria pathogen’s life cycle and disease development is essential for understanding the vaccine. The life cycle begins when the female anopheles transfers Plasmodium falciparum to human blood in the form of sporozoites.

These sporozoites travel with the person’s blood and reach the liver. They undergo physical changes and transform into trophozoites.

The trophozoite nuclei divide several times without a division in the cell wall. This results in multi-nucleated cells known as schizonts.

Numerous daughter cells emerge from a schizont. These are known as merozoites and they have half the number of chromosomes of the original germs. These are enclosed in capsules called merosomes and released into the blood.

These merozoites enter red blood cells and start a synchronized development all over the body. As they grow, they digest the hemoglobin in the blood cells to release energy for their functions. This decrease in hemoglobin leads to fever and anemia.

Infected blood cells appear deformed and tend to cluster in specific organs like the heart, brain, or liver. Malarial blood cell clustering in the brain is a severe condition that is almost always fatal.

The P. falciparum is transferred to a mosquito that drinks the infected human’s blood, continuing the cycle.

Below is a diagram to aid in a better understanding of the life cycle steps.

Early Attempts At Developing A Vaccine

Finding a vaccine for Malaria posed several challenges. As mentioned above, the malarial parasite has numerous life cycle stages, and each stage has different structural and chemical markers. Thus, a vaccine targeted at any one stage might not prevent the previous stages, and a few pathogens might escape.

Scientists discovered that preventing the stage before the parasite reaches the liver is the best way to stop its growth entirely. This meant that a human’s immune system only had 30 minutes to prevent the next stages of P. falciparum after it reached the blood flow. A potential vaccine should boost immunity enough to make this feat possible.

Another major obstacle was testing the feasibility of the vaccine. Human test subjects need to be guaranteed a complete recovery to ensure the ethical nature of the survey. Scientists achieved this by immediately providing antimalarial antibiotics to any patient who showed even the earliest signs of the disease. It prevented further degradation of health and stopped malaria in its early stages. Thus, the researchers could test the efficacy of vaccine doses without severely affecting a human’s life.

The typical funding for a new vaccine or medical development involves higher charges for first-world countries and lower or free distributions in poorer countries. However, the situation is different for malaria because it mainly affected Southern countries. Many of these areas were economically deprived and unable to fund the majority of the vaccine processes.

As a result, the vaccine’s research and development was funded by WHO, PATH, and the Bill and Melinda Gates foundation. Their donations went a long way in developing an efficient malaria vaccine that reduced vulnerability among the youth.

RTS,S: The First Successful Malaria Vaccine

The first malaria vaccine was developed by a collaboration between the PATH Medical Foundation and GlaxoSmithKline. This vaccine protects against the Plasmodium falciparum protozoan. P. falciparum is the primary cause of concern in Africa, where malaria significantly affects the mortality rates. To reduce this danger, the World Health Organization has now recommended the broad use of this vaccine in South Africa. It is an outstanding achievement for a new vaccine.

The vaccine contains CSP (P. falciparum circumsporozoite protein.) In nature, this protein is released by the protozoans before they attack human red blood cells. When the immune system detects this protein in the vaccine, it automatically launches its defense without the actual pathogen. In case the same person comes into contact with living P. falciparum later, their immune system is strong and prevents infection in their liver cells. The white blood cells also ingest any malaria-infected cells. As a result, the person does not develop malaria.

However, this was not enough. The CSP was minimally successful in the clinical trials because the body does not always detect it. The vaccine had a low success rate. This challenge was overcome by combining the CSP with a protein from the germ that causes Hepatitis B, making it more visible to the body’s immune system. It tricked the immune system into thinking the CSP was part of a virus, which evoked an immediate response. The combination was named the RTS,S vaccine. When researchers administered this vaccine to 8 test subjects, 7 of them displayed immunity to P. falciparum.

The researchers made further improvements. They created RTS,S/AS01 by using a different P. falciparum protein and adding an adjuvant to improve the immune system’s reaction. This vaccine is moderately effective in young children, and less effective in infants. Its protection also decreases over time and a booster dose is required. Mosquirix acquired permission from the European Medicines Agency (EMA) to start giving out the vaccine to infants in 3 African countries.

Results Of The Vaccine

Around 900,000 children received the Malaria vaccine in Ghana, Kenya, and Malawi. It has displayed 30% protection against severe malaria with 4 doses. However, the vaccine still offers significant advantages over the previous situation. Authorities hope that it can prevent child deaths and decrease the risk of cerebral Malaria.

Children aged 5 months or older have received the vaccine, and it is helpful for those who do not use a bed net. However, using a bed net increases the vaccine’s efficiency to around 90%.

Some side effects observed are fever and temporary convulsions. These cases are rare, and the overall vaccine safety is favorable. The vaccine is also affordable and prevents the high costs of malaria treatment after infection.

Looking Forward

WHO aims to include the vaccine in Africa’s long-term malaria prevention program. It will also take steps to acquire more funding for the incorporation. P. falciparum is only one type of malaria pathogen, and the vaccine is partially effective. Further research hopes to diversify the vaccine scope and increase its success rate.