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My main research interests are on viral infections that are transmitted between humans and animals, with a focus on characterising their epidemiology in populations in Africa and developing vaccines for their control.

In our vaccine programme, we exploit synergies in human and livestock immunology to accelerate development of candidate vaccines for deployment in humans and the respective animal hosts of infection. Using this approach, we have developed ChAdOx1 RVF, a novel chimpanzee adenovirus vectored Rift Valley Fever vaccine, that is highly efficacious in multiple target livestock species (sheep, goats, cattle). ChAdOx1 RVF will soon enter human phase I clinical trials in the UK and East Africa and, in parallel, will be evaluated in livestock field trials in Kenya. We have also worked on a similar One Health vaccine project for use against Middle East Respiratory Syndrome (MERS) in camels and humans.

We are also conducting multicentre clinical trials aimed at addressing the global shortage in Yellow Fever (YF) vaccine supply. Though highly effective, providing lifelong immunity following a single immunisation, insufficient YF vaccine is produced for routine use, and the vaccine stockpile reserved for outbreak control is frequently depleted. Our studies aim to determine the immunogenicity of fractional doses of YF vaccine in comparison to that of the full vaccine dose in adults and children in Kenya and Uganda. If any of the lower YF vaccine doses is of comparable immunogenicity to the full vaccine dose, then in effect this finding could have an impact on the number of doses that can be given based on the world’s currently available vaccine stock and the number of doses that are produced for future use, thereby enhance our ability to prevent and control YF outbreaks.

Our virus epidemiology programme is primarily focused on arboviruses (e.g. chikungunya, dengue and zika viruses). Though many of the current arboviral threats were first discovered in Africa, very little is known regarding their distribution, associated disease burden and viral genetic diversity in the continent. We are leveraging our unique biobank, spanning 31 years, at the KEMRI-Wellcome Trust Research Programme in coastal Kenya to address these knowledge gaps. We expect data from these studies to inform target product profiles for candidate vaccines and underpin the design of clinical trials for vaccine efficacy estimation.