Randomised, single blind, placebo - controlled, dose-escalation, phase I clinical trial recruiting healthy adults aged 18-50 years

This is a randomised, single blind, placebo-controlled, dose escalation, phase I clinical trial to assess the safety and immunogenicity of the candidate ChAdOx1 RVF vaccine in healthy Ugandan volunteers aged 18-50. The vaccine will be administered intramuscularly.

This study will run concurrently with the first-in-human ChAdOx1 RVF trial in Oxford. Vaccination at the MRC/UVRI and LSHTM Uganda Research Unit, Masaka will only begin upon receiving a favourable opinion of Uganda's trial DSMB of the 7-day post-vaccination safety analysis of the first two lowest dose groups (ChAdOx1 RVF 5 x 10^9vp and ChAdOx1 RVF 2.5 x 10^10vp) of the trial in Oxford.

Volunteers will be recruited and vaccinated at the MRC/UVRI and LSHTM Uganda Research Unit Clinical Research Centre in Masaka. There will be three study groups and a total of 30 volunteers will be enrolled (table 3). Volunteers will be recruited sequentially into Groups 1,2 and 3. Within each group, eligible volunteers will be randomly allocated to receive either ChAdOx1 RVF or placebo of 0.9% Normal Saline in a ratio of 2:1 in group 1 and 5:1 in groups 2 and 3. The DSMB will analyse the 7-day post-vaccination safety data in each group and advise on whether to proceed to the next group with a higher dose .

Inclusion Criteria:

The volunteer must satisfy all the following criteria to be eligible for the study:

1. Male and female healthy adults aged 18 to 50 years
2. Able and willing to provide written informed consent
3. Able and willing (in the Investigator's opinion) to comply with all study requirements
4. For females only, willingness to practice continuous effective contraception during the study.
5. Females of childbearing potential must have a negative urine β-human chorionic gonadotropin (β-hCG) pregnancy test at screening and a negative urine β-hCG pregnancy test immediately prior to study vaccine administration
6. Agreement to refrain from blood donation during the course of the study
7. Healthy in the investigator's clinical judgement basing on the medical history and physical examination performed at screening
8. Healthy on the basis of clinical laboratory tests (within the institutional normal laboratory reference ranges) performed at screening.
9. Willing to provide verifiable identification to the study team
10. Volunteer must have a means to be contacted or be willing to provide locator information to the study team
11. Volunteer must pass the Test of Understanding (TOU)

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 as it may impact on interpretation of the trial data.
3. Administration of immunoglobulins and/or any blood products within the three months preceding the planned administration of the vaccine candidate
4. 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)
5. History of allergic disease or reactions likely to be exacerbated by any component of the vaccine
6. Any history of hereditary angioedema, acquired angioedema, or idiopathic angioedema.
7. Any history of anaphylaxis in relation to vaccination
8. Pregnancy, lactation or willingness/intention to become pregnant during the study
9. History of cancer (except basal cell carcinoma of the skin and cervical carcinoma in situ)
10. History of serious psychiatric condition likely to affect participation in the study
11. Bleeding disorder (e.g. factor deficiency, coagulopathy or platelet disorder), or prior history of significant bleeding or bruising following IM injections or venepuncture
12. Acute illness or temperature ≥37.5°C/99.5°F on the day of vaccination. Volunteer may be rescheduled for enrolment at a later date.
13. Major surgery (per the investigator's judgement) within 4 weeks prior to screening or planned major surgery through the course of the study
14. Any other serious chronic illness requiring hospital specialist supervision
15. Suspected or known current alcohol abuse as defined by an alcohol intake of greater than 14 units every week
16. Suspected or known injecting drug abuse in the 5 years preceding enrolment
17. Seropositive for hepatitis B surface antigen (HBsAg)
18. Seropositive for hepatitis C virus (antibodies to HCV)
19. Any clinically significant abnormal finding on screening biochemistry, haematology and coagulation blood tests or urinalysis
20. 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
21. Prior natural exposure to RVFV as determined by seropositivity for RVFV antigens by ELISA.