77% Effective Malaria Vaccine Could Pave Way for Eradication of the Disease

May 13, 2021 CATALYST Team

U.S. Army medical researchers taking part in World Malaria Day 2010 in Kenya. U.S. Army Southern European Task Force, Africa. CC BY 2.0.

A recently concluded clinical trial of a new malaria vaccine has shown a promising efficacy rate in the fight against the mosquito-borne disease. Conducted by researchers from Oxford University and the Clinical Research Unit of Nanoro, the new R21/MM vaccine showed an efficacy rate of 77% during a yearlong clinical trial of 450 children in Burkina Faso. The new shot boasts the highest efficacy rate of any malaria vaccine thus far.

One of the reasons why malaria remains such a prevalent disease in sub-Saharan Africa is because the nature of the disease makes it difficult to vaccinate against. Unlike smallpox, polio and COVID-19, all of which are viruses, malaria is caused by the Plasmodium parasite, which is spread through mosquitoes. Parasites are much more complex than viruses because they are living organisms, which makes them more difficult to target due to multiple life stages.

Worldwide, malaria infects over 200 million people annually

That said, R21/MM is unique in that it is a pre-erythrocytic vaccine, a type of vaccine which targets the Plasmodium parasite in its earliest stages of development. This means that R21/MM intervenes before the parasite multiplies in the liver and reaches the bloodstream, a stage in the parasite’s life cycle when no symptoms yet occur.

While R21/MM’s 77% efficacy rate is far lower than that of other vaccines—the smallpox vaccine is 95% effective, the polio vaccine is 90% effective in two doses and all three approved COVID-19 vaccines in the United States are at least 86% effective or higher in preventing severe cases of COVID-19—the new malaria vaccine retains the highest efficacy rate of any options to date.

The most widely used malaria vaccine, RTS,S, which has been used since 2016, only has an initial efficacy rate of 55% and requires booster shots. According to Vox, RTS,S requires four shots to be fully vaccinated initially, whereas the R21/MM vaccine only requires three, plus a booster shot the following year. While numerous required shots makes vaccine rollout difficult, the fact that the new malaria vaccine is significantly more effective than RTS,S and requires one less shot makes it a noteworthy breakthrough in the fight against malaria.

While malaria has been largely eradicated from much of the world, with the U.S. eliminating the disease by 1951 through the application of DDT to the interior surfaces of rural homes, the draining of wetlands and other mosquito breeding sites and the spraying of insecticides, sub-Saharan Africa has continued to be plagued by the disease. Worldwide, malaria infects over 200 million people annually and kills an average of 400,000, with 94% of global malaria cases in 2019 occurring in Africa.

While COVID-19 remains the most pressing global health issue for most countries, in Africa it is malaria which remains most serious.

A December 2020 report by The BMJ estimated that malaria deaths in Africa throughout 2020 would dwarf those caused by COVID-19. As of May 10, 2021, the entire continent of Africa has reported 124,715 deaths due to COVID-19 since the pandemic began, in comparison with the 386,000 deaths reported from malaria in 2019. As a result, malaria vaccines of any efficacy rate are desperately needed in most of sub-Saharan Africa.
According to Al-Jazeera, the researchers of the R21/MM vaccine plan to conduct final stage trials in about 4,800 children between the ages of five months and three years old in four malaria-prone African countries. Should the efficacy rate from the clinical trials remain consistent, R21/MM could finally begin the hard work of eradicating malaria.