Progress toward a long-awaited vaccine for Lassa fever has taken a major step forward as researchers at the Oxford Vaccine Group commence a Phase I human trial of the ChAdOx1 Lassa vaccine. The development signals renewed global momentum to combat a virus that has plagued West Africa for decades and continues to pose a widening threat.

The study, known as VITAL01, is supported by the Coalition for Epidemic Preparedness Innovations (CEPI) and is designed to evaluate the vaccine’s safety and its ability to trigger a protective immune response. It represents the first time this candidate vaccine is being tested in humans—an important benchmark on the path to future clinical phases.

Professor Maheshi Ramasamy, Chief Investigator for the trial, emphasized the broader implications of the research during a December 4, 2025 press briefing. “Vaccines are one of the most powerful tools we have in global health: they save lives, stop outbreaks, and strengthen health systems,” she said. “We’re delighted to start the VITAL01 Lassa fever vaccine study here in Oxford.”

Lassa fever, first identified in the late 1960s, remains endemic in several West African countries and is transmitted primarily through contact with infected rodents or human-to-human transmission in clinical settings. Outbreaks can be severe, and case detection remains difficult due to limited surveillance systems. The World Health Organization lists Lassa fever among its priority pathogens, citing its epidemic potential and the urgent need for research and new countermeasures.

Experts warn that the threat could grow substantially in the coming decades. Projections suggest that as many as 700 million people may live in at-risk regions by 2070. Yet, despite the scale of the danger, no licensed vaccines or widely available treatments currently exist.

The launch of Oxford’s human trial coincides with broader efforts to accelerate vaccine development through the Lassa Fever Coalition—a regional initiative working to harmonize research, strengthen regulatory pathways, and prepare for eventual licensure once promising candidates clear clinical testing.

For global health authorities, the ChAdOx1 Lassa vaccine represents one of the most advanced attempts yet to curtail a virus capable of causing devastating outbreaks. While early-stage trials are only the beginning, researchers and policymakers alike see this moment as an encouraging step toward a future where Lassa fever can be controlled—and potentially prevented entirely.