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On 8 July 2025, researchers at the KEMRI-Wellcome Trust Research Programme began the Phase II trial of the ChAdOx1 RVF vaccine in Kilifi, Kenya—the most advanced Rift Valley fever vaccine study in an outbreak-prone region. Led by Oxford University and funded by CEPI, this milestone brings us closer to a licensed vaccine for protecting lives and livelihoods.

Healthcare worker vaccinating a woman

On July 8, 2025, the clinical trials team at the KEMRI - Wellcome Trust Research Programme began vaccinating volunteers with the ChAdOx1 RVF vaccine candidate in Kilifi, Kenya, as part of a Phase II trial. This is the most advanced stage of testing for vaccines being developed against the potentially deadly disease in an outbreak-affected country – a region where it could be used if this and later stages of testing are successful.

The research study is funded by CEPI and led by University of Oxford, with the promising vaccine candidate using the same technology as the life-saving Oxford-AstraZeneca COVID-19 vaccine.

The launch of the trial is a major vaccine development milestone and takes us closer than ever to having a licensed Rift Valley fever vaccine available for use in people. With Rift Valley fever threatening both people and animals, this work is vital to preventing future outbreaks and protecting both lives and livelihoods. Earlier Phase I studies found the vaccine candidate to be safe and immune-stimulating in volunteers in the UK and Uganda.

CEPI is working to develop vaccines against known threats like Rift Valley fever, and use knowledge and findings to prepare for an unknown ‘Disease X’, in support of the 100 Days Mission. In funding this project, CEPI are boosting regional health security and building systems to more rapidly respond to and prevent new threats. This achievement underscores CEPI’s role as a global health catalyst and demonstrates the impact of continued investment in epidemic preparedness.

 

Read the story on the Centre for Tropical Medicine and Global Health website.