Phase II trials of a “promising” human vaccine candidate against Rift Valley fever are beginning in Kenya with CEPI support. CEPI reported in October 2024 that this is the “most advanced stage of testing” for a human Rift Valley fever vaccine in an “outbreak-prone area”. Scientists at the University of Oxford and the Kenya Medical Research Institute (KEMRI)-Wellcome Trust Research Programme are leading the trial with $3.7 million funding from CEPI.
Rift Valley fever
First identified in Kenya’s Rift Valley, Rift Valley fever is usually found in people after direct contact with infected animals or bites from infected mosquitoes. Most infected people experience “mild disease”, but a small proportion develop the “severe haemorrhagic form”, with a risk of blindness, convulsions, encephalitis, and bleeding. In these cases, mortality rates can reach 50%.
Rift Valley fever has been detected across “much of Africa” and in the Middle East. It is mosquito-borne, which makes it “climate sensitive”. There is therefore a risk of outbreaks spreading to new areas or increasing in frequency or size. There are Rift Valley fever vaccines for animals, but no currently available or licensed vaccines for human use; the disease is a priority disease for R&D for WHO and CEPI.
ChAdOx1 RVF in trial
The vaccine, known as ChAdOx1 RVF, is based on the University of Oxford’s ChAdOx1 vaccine platform. It has shown positive results in healthy adults in the UK, meeting “many of the optimal product characteristics” of a WHO target product profile. It is one of three Rift Valley fever candidates in CEPI’s portfolio. 240 healthy adults will participate in the research, following local trial approvals.
Funding for the trial comes under CEPI’s strategic partnership with the University to accelerate the development of globally accessible vaccines against outbreak pathogens. Both organisations are “committed to enabling access to any vaccine outputs developed through this partnership”, including developing a target product profile suitable for low- and middle-income countries (LMICs), assessing the need for technology transfer, and priority supply to LMICs at an affordable price.
Professor George Warimwe, Principal Investigator of the trail and Deputy Executive Director of the KEMRI-Wellcome Trust Research programme, reflected that “nearly 100 years” after the disease was identified, there are “still no approved vaccines or treatments”.
“This vaccine trial brings us closer to addressing the rising frequency of outbreaks.”
Dr Richard Hatchett, CEO of CEPI, commented that Rift Valley fever “disproportionately affects the lives and livelihoods of vulnerable pastoral communities”, causing human fatalities and livestock losses.
“Investing in the promising human ChAdOx1 RVF vaccine diversifies CEPI’s portfolio and gives us a greater chance at protecting vulnerable populations against this worrisome threat that may become more prevalent with climate change.”
Director General of Africa CDC, H.E. Dr Jean Kaseya, agreed that the disease “leads to livestock losses and human fatalities, thus impoverishing communities who largely depend on livestock for their livelihood”.
“The launch of a Phase II clinical trial of a Rift Valley fever vaccine candidate in an endemic country is a crucial milestone in our efforts to control this disease. Africa CDC is proud to support this initiative that not only prioritises the health of our people but also demonstrates the continent’s growing leadership in advancing clinical research.”
Dr Kaseya stated that the ChAdOx1 RVF vaccine “offers hope to vulnerable populations” who are “disproportionately affected by the growing impact of climate change”.
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