Why Is the Malaria Vaccine Approval a Historic Achievement?

The World Health Organization (WHO) last week endorsed the distribution of the world’s first-ever malaria vaccine. It was also the first vaccine against any parasitic disease.

The vaccine, called RTS,S or Mosquirix, is about 36% effective over the course of four years. But, depending on the number of doses available, it could save between 14,000 and 38,000 children younger than 5 every year if distributed in countries that have the most cases of malaria, according to a modeling study.

“This is a historic moment. The long-awaited malaria vaccine for children is a breakthrough for science, child health and malaria control,” WHO Director-General Tedros Adhanom Ghebreyesus said.

Malaria is a serious and potentially fatal disease spread by mosquitoes. Before the vaccine was available, antimalarial drugs, insecticide-treated mosquito nets, and indoor residual spraying have been used to prevent and reduce malaria transmission.

The vaccine, when combined with seasonal administration of antimalarial drugs, can reduce clinical malaria cases and deaths by around 70%, according to the vaccine developer GlaxoSmithKline.

Why Is the Malaria Vaccine Important?

Malaria is the primary cause of childhood illness and death in sub-Saharan Africa. In 2019, children aged under 5 accounted for 67% of all malaria deaths worldwide.

“Malaria has a devastating effect in rural areas in Africa,” Clive Shiff, PhD, professor at the Johns Hopkins Malaria Research Institute at the Bloomberg School of Public Health, tells Verywell. “It still causes high mortality in rural areas, and has a severe impact on lifestyles, productivity, and of course, illness and death. It cannot be ignored.”

More than 2.3 million doses of Mosquirix have been administered so far in the ongoing pilot program in three countries: Ghana, Kenya, and Malawi. Results show that the vaccine has a favorable safety profile.

“There is continual talk of eradication of malaria, but since the 1950s, this has been through ebb and flow,” Shiff says. “There were times in the mid-20th century when there was local success, but the disease is difficult to eliminate, and management through an effective health system seems the most effective means to control it.”

Having a vaccine as part of national malaria control strategies will help prevent more cases. It will also help the WHO achieve its 2030 goals of reducing malaria case incidence and mortality rates by at least 90%.

Why Did It Take So Long?

Mosquirix was created by scientists in 1987, which means it took around 30 years of thorough research and development.

Unlike the COVID-19 vaccine, which was developed in less than a year, the malaria vaccine had to tackle a much more complex parasite.

James Shepherd, MD, PhD, an infectious diseases specialist at Yale Medicine, says that the COVID-19 virus has 25 genes while the malaria parasite, Plasmodium, has 5,000.

“Finding the perfect fragments of the parasite to induce protective immunity is much more difficult,” he tells Verywell. “Even now, Mosquirix has been in development for more than 30 years and still only provides modest protection compared with most approved vaccines.”

How Does the Malaria Vaccine Work?

Mosquirix is a recombinant protein vaccine, which means it contains a specific part of the germ.

“Mosquirix works like many vaccines—taking a fragment of the infectious organism that is an important target for the immune system to attack, and then making it in large quantities so that it can be injected into people to stimulate protective immunity,” Shepherd says.

Researchers used their expertise from the development of Hepatitis B vaccine and used the surface antigen from the virus as a carrier for the malaria protein, facilitating antibody and T-cell responses.

“If the child subsequently gets bitten by a mosquito carrying malaria parasites, as soon as the parasites are squirted into the bloodstream, the antibodies and T-cells are ready to attack,” Shepherd says.

The malaria parasite can mature, multiply, infect red blood cells, and cause disease if it infects the liver. What the vaccine does is carry antigens that attempt to prevent the first stage of the malaria parasite from entering a liver cell, Shiff explains.

“The malaria parasite has a complex life cycle with several vulnerable stages,” he says. “One is the sporozoite that is injected by a vector species of mosquito, and makes its way to the liver of the human.”

If the parasite can be interrupted before entering further into the human body, it would stop the infection, he adds.

Challenges in Vaccine Distribution

According to the WHO, the global health community will have to make financial decisions regarding the vaccine rollout in the future, and countries need to assess if they will adopt the malaria vaccine as part of their strategy to control the disease.

The vaccine distribution will likely come with some challenges, experts say.

“Most severe cases occur in rural areas where distances are long, and transport difficult,” Shiff says. “It is difficult to ensure each child gets the injection and the several boosters appropriately."

The malaria vaccine can be delivered through child health clinics by the Ministries of Health in respective African countries, which helps increase vaccine coverage in children, Tedros said at a press conference.

Shepherd adds that large-scale implementation trials in Kenya, Malawi, and Ghana showed that Mosquirix is safe and it provides “a decent reduction in incidence of severe malaria.”

“Nevertheless, the vaccine needs three to four shots to protect, and its most impressive impact has been realized when combined with other anti-malaria programs like preventative treatment and insecticide-treated bednets,” he adds. “The logistics and strategic use of Mosquirix remains to be worked out.”

The pilot programs have continued despite the COVID-19 pandemic, and some believe that it’s also feasible to introduce a new vaccine during this time. However, it’s hard to know for sure when the vaccine will start rolling out globally.

"It would be great if, in this world of vaccine inequities, the commercial production of Mosquirix could be transferred to all those countries that will benefit from it most," Shepherd says.