Safety and Immunogenicity of a Candidate RVFV Vaccine (RVF001)

Inclusion Criteria: The volunteer must satisfy all the following criteria to be eligible for the study: 1. Healthy adults aged 18 to 50 years 2. Able and willing (in the Investigator's opinion) to comply with all study requirements 3. Willing to allow the investigators to discuss the volunteer's medical history with their General Practitioner or access this medical history electronically 4. For females only, willingness to practice continuous effective contraception for at least 3 months and a negative pregnancy test on the day(s) of screening and vaccination 5. Agreement to refrain from blood donation during the course of the study 6. Able to provide written informed consent Exclusion Criteria: The volunteer may not enter the study if any of the following apply: 1. Participation in another research study involving receipt of an investigational product in the 30 days preceding enrolment, or planned use during the study period 2. Prior receipt of an investigational vaccine likely to impact on interpretation of the trial data. 3. Prior receipt of any vaccines administered ≤30 days before enrolment and/or planned receipt of a vaccine ≤30 days after enrolment EXCEPT for protein, RNA (or other non-adenovirus based) COVID-19 vaccinations which may be given within 14 days of the trial vaccine. 4. Receipt of a recombinant simian adenoviral vaccine prior to enrolment 5. Planned receipt of another adenoviral vectored vaccine (e.g. Oxford/Astrazeneca or Janssen COVID-19 vaccines) within 90 days after the vaccination with the ChAdOx1 RVF 6. Administration of immunoglobulins and/or any blood products within the three months preceding the planned administration of the vaccine candidate 7. Any confirmed or suspected immunosuppressive or immunodeficient state, including HIV infection; asplenia; recurrent, severe infections and chronic (more than 14 days) immunosuppressant medication within the past 6 months (inhaled and topical steroids are allowed) 8. COVID-19 infection diagnosed in the community in the 28 days prior to enrolment 9. Any main covid-19 symptom within 28 days of enrolment: 1. Fever (subjective or ≥37.8) 2. New continuous cough 3. Loss of sense of smell 4. Loss of sense of taste 10. Clinical suspicion of acute COVID-19 in the 28 days prior to enrolment 11. History of allergic disease or reactions likely to be exacerbated by any component of the vaccine 12. Any history of hereditary angioedema, acquired angioedema, or idiopathic angioedema. 13. Any history of anaphylaxis in relation to vaccination 14. Pregnancy, lactation or willingness/intention to become pregnant during the study 15. History of cancer (except basal cell carcinoma of the skin and cervical carcinoma in situ) 16. History of serious psychiatric condition likely to affect participation in the study 17. Bleeding disorder (eg. factor deficiency, coagulopathy or platelet disorder), or prior history of significant bleeding or bruising following IM injections or venepuncture 18. Any other serious chronic illness requiring hospital specialist supervision 19. Suspected or known current alcohol abuse as defined by an alcohol intake of greater than 42 units every week 20. Suspected or known injecting drug abuse in the 5 years preceding enrolment 21. Seropositive for hepatitis B surface antigen (HBsAg) 22. Seropositive for hepatitis C virus (antibodies to HCV) 23. Any clinically significant abnormal finding on screening biochemistry or haematology blood tests or urinalysis 24. Any other significant disease, disorder or finding which may significantly increase the risk to the volunteer because of participation in the study, affect the ability of the volunteer to participate in the study or impair interpretation of the study data 25. Inability of the study team to contact the volunteer's GP (or access summary care record, if available) to confirm medical history and safety to participate 26. Prior natural exposure to RVFV as determined by seropositivity for RVFV antigens by ELISA and neutralizing antibody assay (serology will be requested at the discretion of the investigator) 27. History of confirmed major thrombotic event (including cerebral venous sinus thrombosis, deep vein thrombosis, pulmonary embolism), history of antiphospholipid syndrome, or history of heparin induced thrombocytopenia