London School of Hygiene & Tropical Medicine

A malaria vaccine has been shown to reduce overall child deaths by 13% in routine use, according to a new study, providing the clearest evidence to date that vaccination against malaria can save lives at scale in high transmission settings.

The findings, published in The Lancet, are based on a four-year evaluation of the RTS,S vaccine in Ghana, Kenya and Malawi, the first countries to introduce it through national immunisation programmes.

The study, led by the World Health Organization and carried out by an international research team including partners in Ghana, Kenya and Malawi, and the London School of Hygiene & Tropical Medicine (LSHTM) , found that vaccinating children against malaria significantly reduced overall mortality among young children in areas where the vaccine was introduced, averting around one in eight deaths in eligible age groups.

According to the researchers, this reduction was observed even though vaccine coverage was incomplete. Around 70% of eligible children received the first three doses of the RTS,S vaccine, while only around 40% received the fourth dose.

This provides strong real world evidence that malaria vaccination is effective when delivered through routine health systems, not just in clinical trials.

The vaccine complemented existing malaria control measures. It reached many children who were not using insecticide treated bed nets, increasing overall protection, and did not reduce uptake of other childhood vaccines or malaria interventions.

Malaria remains the leading cause of post-neonatal under-5 deaths in Africa, with an estimated 438,000 malaria deaths in 2024. Malaria vaccines are now being rolled out in 25 countries, targeting more than 10 million children each year.

The findings suggest that tens of thousands of deaths could be prevented annually as coverage increases. However, funding constraints remain a major barrier to scaling up and sustaining vaccination programmes

Study co-author Paul Milligan, Professor of Epidemiology and Medical Statistics at LSHTM, said: “The true burden of malaria mortality is difficult to measure directly. Many deaths occur at home before a medical diagnosis can be made, and even in hospital settings it can be challenging to determine whether malaria was the primary, a contributory, or merely an incidental factor. For this reason, all-cause mortality was used as the primary outcome in this study. The finding that malaria vaccine introduction with moderate levels of coverage prevented approximately one in eight deaths highlights the very important role malaria plays in child mortality in the regions where the vaccine was deployed.

“The evaluation employed robust methods, including randomised allocation of areas for vaccine introduction. Mortality surveillance was established across three countries and supported by more than 26,000 community-based reporters. Uptake of other childhood vaccines and implementation of malaria control measures were also carefully monitored and remained similar between intervention and comparison areas throughout the study period. Together, these design features strengthen confidence that the reductions in mortality can be attributed to the malaria vaccine rather than to external factors.

“In many settings where malaria vaccines are most urgently needed, delivery is constrained by weak health systems, mistrust, and conflict. While operational research is needed to address these implementation challenges, the results nevertheless show that meaningful reductions in child mortality are achievable even at moderate levels of vaccine coverage, underscoring the potential population-level impact of malaria vaccines under real-world conditions.”

David Schellenberg, Professor of Malaria and International Health at LSHTM and co-author of the study, said: “LSHTM has worked with partners for more than 20 years to evaluate malaria vaccines, from relatively small clinical trials to a pivotal phase 3 trial in seven countries and then to the evaluation of large scale implementation in African countries. Malaria vaccines bring real potential for change in many of the world’s most malarious settings.”

As this was a population level impact assessment, the study did not estimate the level of protection associated with individual vaccine doses. Separate case control studies assessing individual protection have been completed and will be published separately.

Publication

Mwapasa M, Asante KP, Milligan P, et al. Impact of introducing RTS,S/AS01 malaria vaccine on mortality in young children in Ghana, Kenya, and Malawi: an observational evaluation of a cluster randomised implementation programme. The Lancet, 2026. DOI: 10.1016/S0140-6736(26)00248-5