The Coalition for Epidemic Preparedness Innovations (CEPI), the University of Oxford, and the Serum Institute of India (SII) have forged a landmark partnership to create the largest-ever investigational reserve of a Rift Valley fever (RVF) vaccine candidate. This collaborative effort aims to accelerate preparedness and response capabilities against the potentially deadly mosquito-borne disease. Under this licensing agreement, the Serum Institute of India, a leading global vaccine manufacturer, will produce up to 100,000 doses of Oxford's ChAdOx1 RVF investigational vaccine. CEPI is providing significant funding of up to $3.5 million to support the vaccine's development, manufacturing, and the establishment of this crucial reserve. An initial 10,000 doses are designated for an upcoming clinical trial to assess the vaccine's safety and immunogenicity in outbreak-affected regions, while the remaining doses will form a strategic reserve for future rapid deployment. The ChAdOx1 RVF vaccine candidate has already demonstrated promising results, having completed Phase I trials in the UK and Uganda, showing good safety and immune response. A CEPI-supported Phase II trial also commenced in Kenya in 2025. This urgent action comes in response to a severe and ongoing RVF outbreak in West Africa, particularly impacting Senegal and Mauritania, where hundreds of human cases and dozens of deaths have been reported in 2025. There is currently no licensed human vaccine available for Rift Valley fever, making this collaboration a critical step towards global epidemic preparedness. The rapid manufacturing, with SII already filling and labelling 12,000 vials within 16 days of receiving ingredients, highlights the partners' commitment to swift action against emerging infectious threats.