Malaria Vaccine's Achilles' Heel: Its 4th Dose

For decades, millions of children across Africa have fallen sick from malaria, one of the continent's deadliest diseases for the young. But 9-month-old Kenfack has never had it, a feat his mother, Mabel Djoumessi, attributes to the recent arrival of a malaria vaccine, per the AP. "My other children who have never taken the vaccine frequently fall ill," Djoumessi said at Soa District Hospital. More than two years after Cameroon became the first nation to incorporate the RTS,S malaria vaccine into its routine immunization program, health workers say it's reducing severe illness. In Cameroon, one of 11 countries accounting for about 70% of the global malaria burden, per the World Health Organization, malaria remains the leading cause of hospital consultations and admissions.

The nation recorded around 7.6 million malaria cases and 11,700 deaths in 2024. But data from Cameroon's National Malaria Control Program shows health facilities recorded a drop in cases in 2025, with 33,000 fewer than in 2024. Some have cautioned, though, against attributing the decline just to the vaccine. "Isolating the specific impact of malaria interventions requires modeling, and we do not yet have a model to quantify the vaccine's sole contribution," says Dr. Bomba Amougou, the NMCP's head of prevention. Health workers also worry too few children return for the fourth and final shot, or booster, that the WHO says is essential to prolong immunity. The challenge reflects a wider problem with multidose vaccines across Africa.

In a malaria vaccine pilot program across 158 districts in Ghana, Kenya, and Malawi, coverage, or the share of children eligible for each dose, reached about 80% for the first shot, given at around 6 months of age. But it dropped to 46% for the fourth dose, given between 22 and 24 months, per a 2025 study in the peer-reviewed Malaria Journal. Those studying that early rollout found that children missed later doses largely due to transport costs, lack of reminders, poor follow-up, and competing work or childcare responsibilities. Still, the lower vaccination rates are "initial teething problems that I don't think should take the spotlight away from the value of this vaccine," says Dr. Sania Nishtar, CEO of Gavi, the Vaccine Alliance. She also says research efforts continue toward a single-dose malaria vaccine. More here.