Monthly Ivermectin Cuts Malaria Infection by 26% in Kenyan Phase III BOHEMIA Trial

Detailed findings from the Phase III BOHEMIA clinical trial (NCT04966702) in Kenya show that ivermectin administered once per month for 3 consecutive months resulted in a 26% lower incidence of malaria infection when compared to albendazole in children aged 5 to 15 years.¹

Results from the BOHEMIA study, recently published in The New England Journal of Medicine (NEJM), provide evidence to support the use of ivermectin as a promising new vector-control tool amidst rising insecticide resistance and behavioral adaptation in mosquitoes.

Cluster-randomized trial design and treatment coverage

The trial created 96 population clusters totaling over 30,000 people, with 84 clusters (28,932 individuals) deemed eligible.

• Over 93% of treated participants in both the ivermectin and albendazole groups received at least two doses of a study drug.
• The crude cumulative incidence of malaria was 2.20 infections per child-year in the ivermectin group versus 2.66 in the albendazole group.
• Adjusted analysis showed a statistically significant reduction in infection incidence with ivermectin, with an incidence rate ratio of 0.74 (95% CI, 0.58 to 0.95; P=0.02).
• Time to first infection was longer in the ivermectin group (median 120 days) compared to the albendazole group (median 93 days).
• Sensitivity analyses confirmed the primary findings, with incidence rate ratios ranging from 0.48 to 0.76 depending on diagnostic criteria and model specifications.
• A total of 17 serious adverse events were reported, none considered related to treatment.
• The overall adverse event rate was higher in the ivermectin group at 6.19 per 100 treatments, compared to 3.75 in the albendazole group (IRR 1.65; P=0.005).

“The results of our trial were consistent across multiple sensitivity analyses and showed a gradient effect, with higher protection observed among children living farther away from the cluster border and in clusters where the drug was distributed faster,” the study authors wrote. “Our trial showed a community-wide benefit with ivermectin, and the results are aligned with the WHO-proposed minimally required criterion of at least a 20% reduction in the incidence of infection that lasts for at least one month after the completion of a single round of treatment.”

Kenya trial part of broader BOHEMIA program

BOHEMIA is a cluster-randomized, open-label, Phase III study evaluating the safety and efficacy of ivermectin to reduce malaria transmission across two individually powered trials in Mozambique and Kenya. The BOHEMIA program is organized around a central community prevention mass drug administration protocol.²

• The two primary outcome measures were the cumulative incidence of malaria infection in children 5 to 15 years of age, and of adverse events assessed among all eligible study participants.
• Clusters served as the unit of randomization, while efficacy was analyzed based on children aged 5 to 15 living within the clusters.
• Clusters were algorithmically defined using household coordinates and required a core area with at least 35 children aged 5 to 15.
• A 400-meter buffer zone was added around each core, and overlapping buffers were not allowed, ensuring a minimum distance of 800 meters between cluster cores.

Ivermectin offers novel mechanism for vector control

“Mass administration of ivermectin would be a drug-based approach to vector control that leverages a mechanism of action that is distinct from that of the currently used insecticides in public health programs,” the authors concluded. “This innovative method not only enhances vector control but provides potential collateral benefits in areas in which neglected tropical diseases, such as scabies and diseases caused by soil-transmitted helminths and filariae, are also endemic, particularly if existing delivery systems are leveraged for the distribution of ivermectin.”

References

1. Carlos Chaccour, MD, PhD, et al., Ivermectin to Control Malaria — A Cluster-Randomized Trial. New England Journal of Medicine. https://www.nejm.org/doi/full/10.1056/NEJMoa2411262. (2025)

2. Broad One Health Endectocide-based Malaria Intervention in Africa (BOHEMIA) (BOHEMIA). ClinicalTrials.gov. Updated March 14, 2025. Accessed August 1, 2025. https://clinicaltrials.gov/study/NCT04966702