Evaluating immune responses to vaccines for yellow fever and Japanese encephalitis

An Experimental Medicine Decipher of a Minimum Correlate of Cellular Immunity

This study is testing how well different combinations of yellow fever and Japanese encephalitis vaccines work in healthy adults to see if they boost the immune response.

Quick facts

• Phase: Phase 2
• Study type: Interventional
• Enrollment: 70 (estimated)
• Ages: 21 Years to 45 Years
• Sex: All
• Sponsor: Singapore General Hospital (Academic / other)
• Locations: 1 site (Singapore)
• Trial ID: NCT05568953 on ClinicalTrials.gov

What this trial studies

This clinical trial aims to assess the immune response in healthy adults following vaccination with different combinations of yellow fever and Japanese encephalitis vaccines. Participants will be randomized into two groups receiving either the JE-YF17D vaccine followed by the YF17D vaccine or vice versa, with a third group receiving an inactivated JE vaccine. The primary objective is to compare levels of viremia after a challenge with a structurally heterologous virus. The study will involve thorough screening and informed consent processes to ensure participant safety and understanding.

Who should consider this trial

Good fit: Ideal candidates for this study are healthy adults aged 21-45 who are willing to comply with study procedures.

Not a fit: Patients with significant health issues or those outside the specified age range may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could enhance vaccine strategies against yellow fever and Japanese encephalitis, potentially leading to better protection against these viral infections.

How similar studies have performed: Other studies have shown promise in evaluating immune responses to similar vaccine combinations, indicating potential for success in this approach.

Eligibility criteria

Inclusion Criteria:

1. Healthy adults, 21-45 years of age at time of screening
2. Willing to comply to study procedures and adhere to study schedule visits.
3. Satisfactory baseline medical assessment as assessed by physical examination and a stable health status. The laboratory values must be within the normal range of the assessing site or show abnormalities that are deemed not clinically significant as judged by the investigator. A stable health status is defined as the absence of a health event satisfying the definition of a serious adverse event.
4. Accessible vein for blood collection.
5. Ability to provide informed consent.
6. Female subjects of non-child bearing potential due to surgical sterilization (hysterectomy or bilateral oophorectomy or tubal ligation) or menopause. Post-menopausal subjects must have had at least 12 months of natural (spontaneous) amenorrhea
7. Female subjects of child bearing potential with negative urine pregnancy tests on the day of screening and vaccination.
8. Both male (if he has a partner of childbearing potential) and female subjects (of childbearing potential) must agree to use adequate and reliable contraceptive measures (e.g. spermicides, condoms, contraceptive pills) or practice abstinence for 10 days after vaccination.

Exclusion Criteria:

1. History of presence of cardiovascular, respiratory, hepatic, renal, gastrointestinal, neuropsychiatric, haematological, endocrine or immunosuppressive disorders that would be a risk factor when administered the investigational product (IP)
2. Previous receipt of Imojev, Stamaril or Ixiaro vaccines, or any other yellow fever or Japanese encephalitis vaccines
3. Previous history of Yellow fever virus or Japanese encephalitis infection
4. Known allergy to Imojev, Stamaril or Ixiaro vaccines or their components
5. History of severe food/drug/vaccine allergies e.g. angioedema, anaphylaxis
6. Known allergy to egg or egg products
7. History of thymus gland disease
8. Diagnosed with cancer or on treatment for cancer (with the exception of localized basal cell carcinoma) within 3 years prior to screening
9. Evidence of clinically significant anemia (Hb \<10 g/dl)
10. Blood donation exceeding \>450mls in the past 3 months
11. Presence of acute infection in the preceding 7 days or presence of a temperature ≥ 38.0°C (oral or tympanic temperature assessment), or acute symptoms greater than of "mild" severity on the scheduled date of first dose
12. Woman who is pregnant or breast feeding
13. Evidence of substance abuse, or previous substance abuse including alcohol
14. Participation in a study involving administration of an investigational compound (including investigational vaccines) within the past three months, or planned participation during the duration of this study.
15. Receipt of anti-inflammatory drugs (such as NSAIDs or systemic steroids) in the past 7 days.
16. Receipt of any licensed vaccine in the past 30 days before the first study vaccine dose.
17. Positive serum Dengue IgG by ELISA
18. Any condition that, in the opinion of the investigator, would complicate or compromise the study or wellbeing of the subject.

Where this trial is running

Singapore

• SingHealth Investigational Medicine Unit — Singapore, Singapore (Recruiting)

Study contacts

• Principal investigator: Shirin Kalimuddin, MRCP (UK) — Singapore General Hospital
• Study coordinator: Jin Ying Ng

Conditions Infectious Disease; Yellow Fever; Japanese Encephalitis; Viral Infection; YF17D; JE-YF17D; T-cell Immunity; Cellular Immunity