The World Health Organization (WHO) has designated Lassa fever as a priority pathogen, emphasizing the urgent need for research and development given its potential to cause epidemics.
In a statement on Thursday, WHO announced that the Oxford Vaccine Group has administered the first dose to a volunteer in a first-in-human trial of a Lassa fever vaccine, calling it a major milestone in the battle against the deadly virus.
The trial, led by the Oxford Vaccine Group and funded by the Coalition for Epidemic Preparedness Innovations (CEPI), will evaluate the safety and immune response of the ChAdOx1 Lassa vaccine, involving 31 participants aged 18–55. WHO notes that Lassa fever, caused by the Lassa virus and primarily spread by rodents, can result in severe illness, including deafness, bleeding, and death.
The CEPI-funded trial is taking place in Oxford, with a second phase 1 trial planned in Ghana for early 2026. WHO highlighted that Lassa fever, first identified in Nigeria in the late 1960s, is endemic in West Africa and has been classified as a priority pathogen due to its outbreak potential and the lack of licensed vaccines or treatments. Experts estimate that by 2070, up to 700 million people could be living in areas at risk of Lassa fever.
The vaccine, developed by researchers at the Pandemic Sciences Institute, University of Oxford, uses the same viral vector platform as the Oxford/AstraZeneca COVID-19 vaccine, which is estimated to have saved six million lives in its first year.
Prof. Maheshi Ramasamy, Chief Investigator of the trial at the Oxford Vaccine Group, described vaccines as one of the most powerful tools in global health.
“They save lives, stop outbreaks, and strengthen health systems. We’re delighted to start the VITAL01 Lassa fever vaccine study here in Oxford. Building on Oxford’s world-leading experience in developing vaccines for emerging infections and pandemics, this study is a crucial step toward protecting vulnerable communities from the devastating impact of Lassa fever. CEPI also supported early preclinical development of the vaccine,” she said.
Dr. Katrin Ramsauer, Lassa Disease Programme Lead at CEPI, said the launch marked a transformative milestone in the fight against Lassa fever.
“In addition to new clinical trials, plans to advance a Lassa vaccine toward licensure are progressing under the regional leadership of the Lassa Fever Coalition, led by the West African Health Organization (WAHO) with CEPI and partners. The consortium brings together West African leaders, public health experts, and vaccine developers to accelerate the equitable introduction of Lassa fever vaccines across affected regions,” she said
Dr. Virgil Lokossou, Director of Healthcare Services at WAHO, emphasized that Lassa fever has affected lives in West Africa for over half a century. He stated, “Now, our region is taking bold steps to change that story. Through collaborative efforts with partners like the University of Oxford under the Lassa Fever Coalition, we are leading the way in confronting this epidemic threat so it no longer undermines our health and societies. Oxford’s vaccine candidate brings real promise, and this clinical trial comes at a time when regional efforts to defeat Lassa fever are stronger than ever.”
