Three promising Lassa fever vaccine candidates are in clinical development, one of which could be licensed in the next decade. But to ensure a swift and effective rollout, West African countries must start planning now to determine who should receive it, how to deliver it, and how to finance and regulate it.
LONDON/ABIDJAN – One of West Africa’s most persistent and underfunded health threats, Lassa fever, still causes preventable deaths more than a half-century after it was discovered. Fortunately, three promising vaccine candidates are in clinical development, one of which could be licensed in the next decade. But this progress will translate into protection only if countries are prepared to use the vaccine.
Lassa fever is a serious disease that disproportionately affects people in rural areas where rodents spread the virus to humans. While many infections go undetected, because symptoms mimic those of other fevers and diagnostics are scarce, the consequences are still significant. To contain transmission, health facilities sometimes close wards, delaying routine care and stretching already fragile systems. The threat extends beyond health care: households lose income and children miss school. Across West Africa, Lassa fever is estimated to cause roughly $160 million in losses each year, largely owing to the negative impact on productivity.
To turn scientific breakthroughs into real immunity, the West African Health Organization (WAHO) and West African health ministers, with support from the Coalition for Epidemic Preparedness Innovations (CEPI), convened the Lassa fever Coalition in 2024. Building on the improvements in surveillance, research, and outbreak response made by national public-health institutes, researchers, and related organizations, the coalition helps support stronger vaccine-trial networks, enable regional data sharing, and develop regulatory capacity and policy frameworks for vaccine introduction and scale-up.
As experience shows, a lack of readiness can delay vaccine uptake. For example, the human papillomavirus vaccine was introduced as a three-dose series, although it was later found that a single dose is just as effective. Dose guidance was eventually updated, cutting delivery costs and expanding coverage in low- and middle-income countries. But the change came 16 years after regulatory approval. One estimate suggests that adopting the one-dose schedule just five years earlier could have saved 150,000 lives.
A future Lassa fever vaccine may face similar delays unless policymakers consider key decisions before regulatory approval. That means devising clear criteria for who should be vaccinated first, weighing the risks faced by health workers and other vulnerable populations. They must also analyze local data to determine where vaccination will have the greatest impact, because risk varies widely between districts and depending on the season. And governments need realistic plans for delivery through existing infrastructure, as well as analyses of costs and options for procurement.
The Lassa fever Coalition’s Policy Research Working Group has collaborated with more than 200 experts across West Africa to identify the highest-priority research questions that must be addressed before distributing a Lassa fever vaccine. Some of these questions are already being answered. The CEPI-funded Enable study is tracking the prevalence of Lassa fever across West Africa – the largest-ever study to do so. The most affected countries have worked with partners for several years to strengthen disease surveillance, improve laboratory systems, and build clinical-trial networks.
But more must be done. National policymakers should begin by identifying the data required to identify high-risk groups and areas, develop delivery strategies, and assess financing needs. Regional bodies such as WAHO should liaise with the relevant institutions to align regulatory processes and create channels for rapid guidance once trial results emerge. Technical agencies and other partners can support the operational research and surveillance improvements that countries cannot carry out alone.
Finally, a vaccine rollout cannot succeed without trust. Community organizations should start building awareness about Lassa fever and instilling confidence about a vaccine long before doses arrive. This is particularly important in communities that fear the disease, or where a stigma is attached to it.
Some argue that it is premature to act when vaccine candidates remain in trials and budgets are tight. Others worry about how people will respond to a new vaccine for a disease with which they may not be familiar. But these very real concerns underscore the need to begin planning and educating now. The long timeline for vaccine development strengthens the case for early action, because building regulatory systems, making financing arrangements, and constructing engagement structures takes years.
True, governments may not need full vaccination plans now. But they should lay the groundwork to ensure clarity on where to roll out the campaign, how to finance it, and what community engagement will look like. That way, by the time a vaccine is licensed, affected countries will be in a better position to act quickly and decisively.
A Lassa fever vaccine would undoubtedly be a major scientific breakthrough. But it will not be much help unless countries are ready for it.
