Baseline skin memory T cells in unvaccinated volunteers
Official title: Baseline Assessment of Skin Resident Memory T Cells in Healthy Unvaccinated Participants (GeKoSkimm-Unvaccinated): add-on Study to the GeKoSkimm Trial (= A Randomized Controlled Trial to Compare the Immunogenicity and Skin Imprinting of Intradermal, Subcutaneous and Intramuscular Yellow Fever Vaccination)
Run by Institute of Tropical Medicine, Belgium · NCT07636551 · Data updated 2026-11-12
This study tests the natural baseline levels of skin-resident memory T cells in healthy people who have not received the yellow fever vaccine.
Quick facts
| Study type | Interventional |
|---|---|
| Ages | 18 Years to 50 Years |
| Sex | All |
| Enrollment | 40 (estimated) |
| Sponsor | Institute of Tropical Medicine, Belgium Academic / other |
| Drugs / interventions | prednisone |
| Locations | 1 site (Antwerp) |
| Status | Recruiting |
| Started | August 10, 2026 |
| Main results expected | November 15, 2026 |
| Study ends | November 15, 2026 |
| Registry record updated | August 13, 2026 |
| Trial ID | NCT07636551 on ClinicalTrials.gov |
Is this trial a fit for you?
✓Likely a good fit
Healthy adults aged within the study’s BMI range who have not been vaccinated against yellow fever and consent to skin biopsy and serial blood draws.
✕Probably not a fit
Participants who test positive for yellow fever antibodies or who do not meet vaccination-status criteria will not contribute to the primary analyses.
A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.
What this trial studies
This study will enroll 40 healthy adults who have not been vaccinated against yellow fever. It will measure baseline skin immune cells by taking two small skin punch biopsies and collect blood samples to confirm vaccination status. There are two visits spaced about two weeks apart; participants who test positive for yellow fever antibodies will be excluded from analyses. No vaccination or treatment is administered as part of this study; the goal is to understand normal immune presence in skin before any vaccine exposure. The findings will help interpret responses in related vaccine studies that compare different routes of yellow fever vaccination.
Why it matters
Potential benefit: Participants may not directly benefit, but the study could advance understanding of how skin immune cells behave in healthy individuals.
How similar studies have gone: Prior work in related vaccine studies has shown that skin immune landscapes can influence vaccine responses, though this exact baseline skin TRM assessment in unvaccinated individuals is relatively novel.
Who can join: the full rules
Show full inclusion / exclusion criteria
Inclusion Criteria: * BMI \>/=18,5 kg/m2 and ≤35 kg/m2 * Agreement to share and discuss participant's medical history and medical records when relevant with the study team * Able and willing to provide written informed consent * Agreement to refrain from blood donation and other vaccinations during the study Exclusion Criteria: * Participants with a confirmed flavivirus infection in the past * Participants who received a flavivirus vaccination prior to enrolment (e.g. YFV, Japanese encephalitis virus, tick-borne encephalitis virus, Dengue) * Receipt of any vaccine (licensed or experimental) within 30 days prior to enrolment or during the study * Active participation in another interventional clinical study with active substance intake or large medical procedures affecting the study procedures during or 1 month prior to enrolment * Participant has a clinically significant acute illness (this does not include minor illnesses such as diarrhea or mild upper respiratory tract infection) or temperature ≥38.0ºC within 24 hours prior to the visit; inclusion at a later date is permitted at the discretion of the investigator * Any confirmed or suspected immunosuppressive or immunodeficient state (incl. cancer and human immunodeficiency virus/hepatitis B virus infection); asplenia; recurrent severe infections and use of immunosuppressant medication (including antineoplastic and immunomodulating agents or radiotherapy) within the last 6 months prior to enrolment, except topical or short-term oral steroids (\<2 weeks of daily receipt of 20 mg of prednisone or equivalent). Refer to annex 1 for a list of immunosuppressive medication * Severe and/or uncontrolled cardiovascular disease, respiratory disease, gastrointestinal disease, liver disease, renal disease, endocrine disorder, psychiatric and neurological illness (mild/moderate well controlled comorbidities are allowed) * History of bleeding disorder (e.g. factor deficiency, coagulopathy or platelet disorder), or prior history of significant bleeding or bruising following venipuncture * Any significant disease, disorder or planned surgery which may affect the ability of the volunteer to participate in the study or impact (skin) immunity homeostasis * Suspected or known alcohol or drug dependency * Known pregnancy * Tendency to keloid (scar) formation in response to skin damage * Skin diseases or tattoo at the biopsy site * In the opinion of the investigator, unlikely compliance to the requirements of the study * History of thymus dysfunction (including myasthenia gravis, thymoma) or thymectomy * Individuals who are working at the investigational site or within the research team of this study * Participants who received immunoglobulins and/or any blood or blood derived products within 3 months preceding the study * Participants who are currently on anticoagulant therapy * Participants who are continuously using systemic antivirals
Where it's running
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Clinical Trial Site of the Institute of Tropical Medicine
Antwerp, Belgium Recruiting
Study contacts
- Study coordinator: Prof. Dr. Patrick Soentjens
- Email: psoentjens@itg.be
- Phone: +3232476641
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How to take part
- Review the eligibility criteria above with your treating physician.
- Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
- Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.