Health-economic impacts of age- and sex-targeted Lassa fever vaccination in endemic regions of Nigeria, Guinea, Liberia and Sierra Leone: a modelling study

Journal article

Background: Lassa fever is an emerging zoonotic disease endemic to west Africa. Several vaccines aimed at preventing Lassa fever are currently under development, creating a need to assess how best to administer them once licensed for human use. We aimed to project the health-economic burden of Lassa fever from 2025 to 2037 across age and sex groups in subnational administrative divisions of west Africa with endemic Lassa mammarenavirus transmission and to estimate the cost-effectiveness of targeting Lassa vaccination to different risk groups.

Methods: In this vaccine-impact modelling study, we developed a mathematical model using a zoonosis risk map and epidemiological data from recent and ongoing cohort studies to predict the health-economic burden of Lassa fever across age and sex groups in endemic regions. We simulated vaccination campaigns targeting different risk groups to estimate the cost-effectiveness of various strategies for Lassa vaccine administration. Threshold vaccine costs (TVCs), which represent the break-even price per dose of vaccine administered, were estimated in international dollars (INT$ 2023), accounting for health-care costs, productivity losses, and monetised disability-adjusted life-years (DALYs) averted by vaccination.

Findings: Lassa fever was estimated to cause 6·23 (95% uncertainty interval (UI) 4·21–8·42) hospitalisations, 0·75 (0·48–1·10) deaths and 31·1 (17·7–52·2) DALYs per 100 000 person-years. Vaccine strategies targeting adolescents–adults aged 15–49, older adults aged 50 years and older, and women of childbearing age (WCBA) aged 15–49 years prevented, respectively, the most hospitalisations, deaths, and DALYs per 100 000 vaccine doses. Under base case assumptions, the most cost-effective strategy (greatest net monetary benefit) was untargeted vaccination for a vaccine costing intl dollar2 per dose, and targeting adolescents–adults at intl dollar5 per dose. At intl dollar10 per dose or more, none of the considered strategies were cost-effective. The highest TVC for a single-dose vaccine was estimated at intl dollar7·39 (95% UI 4·33–11·60) when targeting adolescents–adults, followed by intl dollar6·69 (4·17–9·85) when targeting older adults, intl dollar6·10 (3·56–9·74) when targeting WCBA, and intl dollar1·94 (1·10–3·10) when targeting children.

Interpretation: Targeting of adolescents–adults appears to generate the greatest health-economic value per vaccine dose. However, the most cost-effective vaccination strategy will depend on vaccine price.

Authors: Smith, DRM; Oliver, MCA; Holohan, KM; Street, HR; Hollingsworth, TD

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Elsevier
• Journal: Lancet Global Health
• Volume: 14
• Issue: 2
• Pages: e261-e271
• Publication date: 2026-01-07
• Acceptance date: 2025-10-26
• DOI: 10.1016/S2214-109X(25)00450-4
• EISSN: 2214-109X
• Language: English