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New malaria jab also reduces other fatalities

The roll-out of malaria vaccines in Africa – the world’s first routine immunisation programme against the disease – has a surprising added benefit, reducing all kinds of deaths among children, not just malaria fatalities, by 13%, say experts.

The RTS,S vaccine is “not only a huge step forward for malaria control but also a major advancement in child health,” Dr Mary Hamel, the WHO’s senior technical officer on malaria, told NPR.

The 13% statistic came from a successful WHO pilot campaign in Ghana, Kenya and Malawi, where more than 2m children aged between five months and two-years-old, have received the malaria vaccine since 2019.

Developed by GlaxoSmithKline, the RTS,S vaccine prevented about 39% of malaria cases and 32% of severe cases in phase 3 trials, as compiled by WHO.

“While 39% efficacy seems low for a vaccine, when we consider the sheer burden of malaria, this means potentially a huge reduction in cases and deaths among children,” said Dr Aaron Samuels, CDC’s Kenya malaria programme director, in 2021.

In 2022, there were an estimated 249m cases of the disease globally and 600 000 deaths. Africa was home to 95% of these deaths, including almost half a million children under five.

The new vaccine does present some challenges: children need four doses over a year to be fully vaccinated, which may be difficult to co-ordinate outside clinical trial settings. A huge quantity will be needed, and each dose costs about $9.80.

There had also been concerns about getting an adequate supply from pharma company GSK.

But the approval of a second malaria vaccine by WHO, called R21/Matrix-M, should help address shortages in vaccine coverage as it requires only three doses, each costing $2-$4, with 100m doses expected to be available later this year.

The RTS,S vaccine campaign began last Monday in Cameroon, with the goal of reaching 6.6m children across 20 African countries by 2025.

Dr Kate O’Brien, director of the Department of Immunisation, Vaccines and Biologicals at WHO, expects the scale-up of the vaccine to save tens of thousands of lives annually.

An unexpected bonus

Certainly, some of these averted deaths will be directly related to malaria. But the unexpected development is that the vaccine seems to reduce deaths where malaria is only a contributing factor, exacerbating other diseases but not killing the patient itself, according to Dr Steve Taylor, a global health and infectious disease expert at Duke University in the US.

As an example, he notes that contracting malaria makes you more likely to get salmonella disease – the most common bloodstream infection in Africa with a case fatality of up to 20%-25%. Malaria also seems to make people susceptible to bacterial infections more broadly, with a Lancet study out of Eastern Kenya in 2011 demonstrating that over half of bacteraemia cases were attributable to malaria.

Hamel said children who have HIV or face chronic malnutrition are at higher risk of severe malaria, which in turn can exacerbate HIV and malnutrition, potentially leading to death.

“We have seen this before with malaria,” she said. “In trials where children got insecticide-treated nets or preventive antimalarial tablets, the reduction in mortality is more than what one would expect from a decrease in malaria deaths alone.”

Decreasing non-malaria deaths is not the only spillover benefit of the vaccine.

“Malaria is a major reason for school absenteeism, anaemia and impaired cognitive development,” said Dr Mohammed Abdulaziz, head of disease control and prevention at Africa CDC. “This vaccine is a crucial element in improving African children’s educational outcomes and cognitive ability, which can help break the cycle of adversity plaguing our youth.”

The vaccine comes at an important time, as malaria caseloads have been steadily increasing from 209m to 233m in Africa, between 2000-2022.

“We’ve had resurgences in a lot of places and particularly during the pandemic,” said Dr Chris Plowe, a malariologist at the University of Maryland.

“A lot of progress that was made in the first part of the 21st century has plateaued and, in some places, reversed.”

Climate change, for instance, has contributed to increased malaria exposure in sub-Saharan Africa, and growing drug and insecticide resistance has made fighting malaria more difficult.

“The parasite is so plastic, so malleable, so quickly able to evolve all of these interventions,” Plowe added. “If you let up pressure, it will evolve, it will change, it will come back.”

The malaria vaccine will usher in a “transformative chapter in Africa’s public health history”, Africa CDC’s Abdulaziz said.

“It brings more than just hope. It brings a reduction in the mortality and morbidity associated with malaria.”