Could vaccinating adults against malaria materially reduce adult mortality in high-transmission areas?

Abstract

After a period of unprecedented progress against malaria in the 2000s, halving the global disease burden by 2015, gains overall in sub-Saharan Africa have slowed and even reversed in some places, beginning well before the COVID-19 pandemic. The highly effective drugs, treated nets, and diagnostics that fueled the initial progress all face some threats to their effectiveness, and global funding to maintain and increase their use over the long term is not guaranteed. Malaria vaccines are among the most promising new interventions that could accelerate the elimination of malaria. Vaccines are still in early stages of rollout in children, the age group (along with pregnant women) that has been the focus of malaria strategies for a century. At the same time, over the past decade, a case has been made, based largely on evidence from verbal autopsies in at least a few high-transmission areas, that the malaria death rate among adults has been greatly underestimated. Could vaccinating adults help to bring down the adult malaria mortality rate, contribute to reduced transmission, or both? A randomized trial of a malaria vaccine is proposed in Sierra Leone, a highly endemic setting, to shed light on this proposition.

Keywords: Adult mortality; Malaria; Vaccines.

Fig. 1

Comparison of progress in malaria mortality rate in the WHO African Region considering two scenarios: current trajectory maintained and GTS targets achieved Source: World Malaria Report 2022 (Fig. 8.4.b)

Fig. 2

Malaria age-specific death rates in African INDEPTH sites, 2000–2012, and Sierra Leone, 2016–2022 Sources: Gelband et al., [3], Carshon-Marsh et al., [2], and unpublished data from Sierra Leone