Article Impact Level: HIGH Data Quality: STRONG Summary of Nature Medicine. https://doi.org/10.1038/s41591-024-03232-y Dr. David R. M. Smith et al.
Points
- With pandemic potential recognized by WHO, Lassa fever causes significant health and economic burdens in West Africa, with an estimated 2.7 million infections annually and 2.0 million disability-adjusted life years (DALYs) lost over a decade.
- The study found that the most effective approach to reducing the impact of Lassa fever is a population-wide preventive vaccination campaign, especially in WHO-identified endemic districts.
- Preventive vaccination could save approximately $20.1 million in DALY losses and $128.2 million in broader societal costs, highlighting the significant economic benefits of over-reactive strategies.
- Reactive vaccination strategies, initiated after outbreaks, are far less effective, averting only a fraction of the health and economic burden compared to preventive measures.
- The study also modeled a potential Lassa virus pandemic variant, “Lassa-X,” showing that achieving WHO vaccination targets could prevent 22% to 74% of DALYs, depending on vaccine efficacy, underscoring the importance of efficient vaccination programs.
Summary
Lassa fever, recognized by the World Health Organization (WHO) for its pandemic potential, inflicts significant health-economic burdens across West Africa. A comprehensive analysis incorporated into this study estimates approximately 2.7 million Lassa virus infections annually, translating to about 2.0 million disability-adjusted life years (DALYs) lost over a decade, with an uncertainty interval of 793,800 to 3.9 million. The study utilizes a detailed model to forecast the regional impact of Lassa fever and explores the efficacy of various vaccination strategies in mitigating this impact. Notably, a population-wide preventive vaccination campaign, mainly targeting districts identified as ‘endemic’ by the WHO, emerged as the most effective method.
The economic evaluation of these vaccination strategies reveals significant potential savings. Even under conservative efficacy assumptions, the preventive vaccination strategy could avert approximately $20.1 million in DALY losses (range $8.2–$39.0 million) and save about $128.2 million in broader societal costs (values in 2021 international dollars). In stark contrast, reactive vaccination strategies, triggered by local outbreaks, were notably less effective, averting just a tenth of the health-economic burden compared to preventive approaches. This stark disparity underscores the value of proactive public health interventions.
Furthermore, the study models a hypothetical scenario involving ‘Lassa-X,’ a potential pandemic variant of the Lassa virus. In the event of such an outbreak leading to approximately 1.2 million DALYs within two years, achieving the WHO’s 100 Days Mission vaccination targets could prevent 22% of DALYs with a vaccine 70% effective against the disease. Should the vaccine prevent infection, up to 74% of DALY losses could be averted. These projections highlight the critical role of efficient vaccination programs in controlling endemic diseases like Lassa fever and preparing for potential pandemics.
Link to the article: https://www.nature.com/articles/s41591-024-03232-y
References Smith, D. R. M., Turner, J., Fahr, P., Attfield, L. A., Bessell, P. R., Donnelly, C. A., Gibb, R., Jones, K. E., Redding, D. W., Asogun, D., Ayodeji, O. O., Azuogu, B. N., Fischer, W. A., Jan, K., Olayinka, A. T., Wohl, D. A., Torkelson, A. A., Dinkel, K. A., Nixon, E. J., … Hollingsworth, T. D. (2024). Health and economic impacts of Lassa vaccination campaigns in West Africa. Nature Medicine. https://doi.org/10.1038/s41591-024-03232-y
