Improving Vaccine Protection for Adults

Recruiting now · Phase 2 · Has a placebo group

Conditions studied: Immune System Responses and Trained Immunity After AS01 Administration, Healthy Adult

In brief

As people grow older, their immune system - the body's natural defence against diseases - becomes weaker, making them more vulnerable to infections and less responsive to vaccines. This was clearly seen during the COVID-19 pandemic, where older adults were more likely to develop severe illness. Researchers have made an interesting discovery about AS01, an ingredient already used in successful vaccines like the shingles vaccine. They found clues that AS01 might work like a general fitness trainer for the immune system, potentially making it stronger and better at fighting off various types of infections, not just specific ones. To confirm this possibility, we are conducting this research study with adults aged 21-59 to test whether AS01 by itself can boost and train the immune system, how long this boost lasts, and if it actually helps you fight off other infections more effectively.

Key facts

Study ID

NCT07527247

Run by

Singapore General Hospital

People needed

40

Starts

2025-11-06

Expected to finish

2029-02-28

Last updated by the study team

2026-06-15

Who can join

Age: 21 and older, up to 59. Sex: any. Healthy volunteers: accepted.

You may qualify if…

• Adults aged 21 to 59 years of age at time of screening.
• BMI 18.5 - 27.5 kg / m2 (BMI values for Asian population according to MOH guideline NIH Consensus Conference).
• Satisfactory baseline medical assessment as assessed by physical examination and a stable health status. For subjects with underlying comorbidities, the conditions must be deemed stable by the investigators, and they must not have any hospitalisation relating to these conditions in the last 6 months.
• Voluntarily participate, understand and sign an informed consent form approved by the Ethical Review Board.
• Subjects who are willing to comply with the requirements of the study protocol and scheduled visits. These requirements include completion of the subject diary, return for follow-up visits. Subjects should also be willing to make themselves available for the duration of the study, with access to a consistent means of contact.
• Accessible vein at the forearm for blood taking.
• Female subjects of non-childbearing potential due to surgical sterilisation (hysterectomy or bilateral oophorectomy or tubal ligation) or menopause. Post-menopausal subjects must have had at least 12 months of natural (spontaneous) amenorrhoea.

You may not qualify if…

• Previous vaccination against yellow fever, dengue either with a registered product or from participation in a previous vaccine study.
• Previously received AS01-adjuvanted vaccines (e.g. Recombinant zoster vaccine, RTS,S/AS01, RSVPre-F3-AS01), either with a registered product or from participation in a previous vaccine study.
• Planned administration of a AS01-adjuvanted vaccine or yellow fever vaccine other than the study vaccine during the study.
• Subjects who have been unwell in the last 7 days prior to screening.
• History of documented yellow fever and / or dengue infection.
• Dengue seropositivity upon screening.
• History of smoking within the last 1 year.
• Planned travel to yellow fever endemic countries during the study.
• Known allergy to AS01 and YF17D vaccine or their components (e.g. egg products).
• Diagnosis of diabetes HBA1c > 6.5 according to American Diabetes Association criteria62.
• Any medical condition that in the judgment of the investigator will make intramuscular injection unsafe (e.g. thrombocytopenia with platelet count < 50x10\^9/L, coagulopathy, anti-coagulant therapy).
• Risk factor for live-attenuated vaccines, including any confirmed or suspected primary or acquired immunodeficiency based on history and physical examination:
• History of thymus gland disease
• Haematologic neoplasms including leukaemia, lymphoma, myelodysplastic syndromes
• Diagnosed with cancer or treatment for cancer (except for localised basal cell carcinoma) within 3 years prior to screening
• Post-transplant: solid organ and haematopoietic stem cell transplant
• Immunocompromised due to primary or acquired (including HIV/AIDS) immunodeficiency
• Other significantly immunocompromising conditions
• Administration of anti-inflammatory drugs for the past 7 days (e.g. NSAIDs, Paracetamol, aspirin).
• Use of metformin for the last 1 month.
• Use of corticosteroids within the last 6 months prior to the first vaccine dose (defined as prednisolone > 10 mg / day or equivalent for > 2 weeks, or prednisolone > 40mg / day or > 1 week). Inhaled and topical steroids are allowed.
• Received biologics (such as anti-TNF inhibitors, IL-1 inhibitors, co-stimulation blockers, B-cell depleting therapy) for the last 12 months.
• Any condition (e.g. extensive psoriasis, chronic pain syndrome, severe hearing loss, cognitive impairment, dialysis, autoimmune disorders) that in the opinion of the investigator, would complicate or compromise the study or wellbeing of the subject, or prevent completion of the study.
• Evidence of substance abuse, or previous substance abuse.
• Clinically significant anaemia (Hb < 10 g/dL).

Where it is running

• Singapore General Hospital — Singapore, Singapore (enrolling)

Full record on ClinicalTrials.gov

Trial information comes from ClinicalTrials.gov and is refreshed daily. TrialsForMe does not provide medical care and does not run the studies it lists.