A Study of SII Yellow Fever Vaccine to Compare Safety and Immunogenicity With STAMARIL

Inclusion Criteria:

1. Male or female volunteers aged ≥ 1 year

2. Healthy volunteers as determined by medical history and clinical examination

3. Participants willing to adhere to the protocol requirements and to provide informedconsent for participants ≥ 18 years of age. For participants < 18 years of age,parental/guardian ability and willingness to provide informed consent (as per localrequirements/procedures) and additional informed assent from participants, asappropriate for participating community (i.e. participants at least 7 years of agein Kenya)

4. Intend to remain residing in study area throughout the study participation

5. Female participants of childbearing potential* must have practiced adequatecontraception** and agree to continue adequate contraception till Day 28post-vaccination.

6. Female participants of childbearing potential must have a negative pregnancy testwithin 24 hours prior to IP administration.

7. Be willing to avoid the use of traditional/herbal local medications and treatmentsfor the duration of the study

Exclusion Criteria:

1. Fever (> 37.5°C) or any clinically significant acute infection at time ofvaccination [Temporary exclusion criteria - participants may be re-screened at least 48 hours after the last recorded fever]

2. Use of systemic (oral or parenteral) antibiotics or antiviral agents within the past 7 days. [Temporary exclusion criteria - participants may be re-screened at least 7days after last dose of antibiotics or antiviral agents]

3. Use of traditional/herbal local medications and treatments in the past 7 days [Temporary exclusion criteria - participants may be re-screened at least 7 daysafter last consumption of traditional/herbal local medications and treatment]

4. Previous history of laboratory confirmed infection with yellow fever and otherflaviviruses e.g., dengue fever, tick-borne-encephalitis (TBE), Japaneseencephalitis (JE), West Nile virus (WNV), zika virus, etc.

5. Previous vaccination against yellow fever, TBE, JE, or dengue fever.

6. Receipt of any vaccine within past 28 days or planned vaccination until completionof Day 28 visit

7. Known or suspected impairment of immunological function based on medical history andphysical examination.

8. Presence of any systemic disorder (cardiovascular, pulmonary, hepatic, renal,gastrointestinal, hematological, endocrine, immunological, dermatological,neurological, cancer, or autoimmune disease) as determined by medical history and /or physical examination which would compromise the participant's health or is likelyto result in nonconformance to the protocol

9. History of chronic administration (defined as more than 14 consecutive days) ofimmunosuppressant (> 0.5 mg/kg/day of prednisolone or equivalent) or other immunemodifying drugs including the use of glucocorticoids. The use of topical/inhaled/pernasal glucocorticoids will be permitted.

10. A known hypersensitivity to any of the vaccine components (including gelatin, eggs,egg products, or chicken protein) or history of a life-threatening reaction to anypast vaccine.

11. Receipt of any immunoglobulin therapy and / or blood products in the past 60 days orplanned administration until completion of Day 28 visit.

12. Participation in a drug research study, involving investigational products, withinpast 3 months or planned participation during the entire study period

13. Receipt of any investigational or unlicensed medication (drug or vaccine) in thepreceding 28 days, or planned use until completion of Day 28 visit

14. Uncontrolled coagulopathy or blood disorder contraindicating subcutaneous injectionsor blood sampling

15. Be an employee of, or direct descendant (child or grandchild) of any person employedby the investigator or sponsor.

16. Pregnant or lactating women

17. Requirement of Yellow Fever vaccination certificate for travelling purpose

18. History of thymus dysfunction including myasthenia gravis, thymoma, thymectomy

19. History or presence of significant alcoholism or drug abuse in the past one year

20. Major congenital or genetic defect

21. Any other condition which in the opinion of the investigator will jeopardize thesafety of the participant or compromise the assessment of the study objectives