Yellow Fever (Healthy Volunteers)NCT07636551
Baseline Assessment of Skin Resident Memory T Cells in Healthy Unvaccinated Participants
A study testing Skin punch biopsy and Blood samples in people with Yellow Fever (Healthy Volunteers) and Biopsy/Methods, run by Institute of Tropical Medicine, Belgium at 1 site in Belgium.
Trial summary
In The main GeKoSkimm trial (= A randomized controlled trial to compare the immunogenicity and skin imprinting of intradermal, subcutaneous and intramuscular yellow fever vaccination) the investigators try to understand whether the route of injection (in the muscle, under the skin, or in the skin) when giving the… Read more about this study
- Who is it for?
- Ages 18 to 50 yearsHealthy volunteers can take part
- Conditions the study is for
- Yellow Fever (Healthy Volunteers), Biopsy/Methods
- What is being tested?
- Skin punch biopsy and Blood samples
- Type of treatment
- Vaccines, Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 40 participants
- Where
- 1 siteBelgium
- Study dates
- 10 Aug 2026to 15 Nov 2026
- Phase
- Interventional
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 50 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- 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
Who cannot join
- 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
Show all 19Show fewer
- 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
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Wim Adriaensen contact
Belgium1 site, 1 recruiting
- Recruiting
Clinical Trial Site of the Institute of Tropical Medicine
Antwerp
Yven Van Herrewege, +3232476557, yvanherrewege@itg.be
Jorge Reis Guerreiro, jreis@itg.be
About this study
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)
In The main GeKoSkimm trial (= A randomized controlled trial to compare the immunogenicity and skin imprinting of intradermal, subcutaneous and intramuscular yellow fever vaccination) the investigators try to understand whether the route of injection (in the muscle, under the skin, or in the skin) when giving the yellow fever vaccine affects the strength of the body's immune response to yellow fever. More in particular the investigators want to know how well the immune responses are retained in the skin, as this is the place where the virus enters the body after a mosquito bite. This will be important for vaccines against infections transmitted via bites of mosquitoes and ticks, such as yellow fever virus. Because this is the first attempt on human samples and only skin samples after vaccination with yellow fever vaccine are available, the investigators want to assess the baseline or background immune response in 'unvaccinated' skin. Therefore, 40 volunteers will be recruited that have not been previously vaccinated against yellow fever and will not receive a yellow fever vaccine during this study. The participant will be requested to provide two skin samples from the upper arm and a blood sample to confirm their vaccination status regarded to yellow fever.
Read the detailed description
Since baseline punch biopsies were not preferred nor incorporated in the GeKoSkimm trial (= A randomized controlled trial to compare the immunogenicity and skin imprinting of intradermal, subcutaneous and intramuscular yellow fever vaccination) due to ethical and logistical reasons, studying tissue-resident memory T (TRM) cells in a group of healthy unvaccinated participants is necessary to assess natural baseline levels of TRM cells in the skin before vaccination. The presence TRM cells in healthy and unvaccinated individuals provides a fundamental understanding of normal immune function and biological variability. This baseline data is essential for interpreting responses to vaccination in the GeKoSkimm trial and detecting any deviations or abnormalities that may arise and assess the baseline or background immune response in 'unvaccinated' skin. Therefore, 40 volunteers will be recruited that have not been previously vaccinated against yellow fever and will not receive a yellow fever vaccine during this study. The study consists of two study visits with 14 days (+/- 10 days) between each visit. Blood sampling of 15 mL is performed on the first visit (1X 10 mL Li-Hep + 5 mL SST) to confirm the vaccination status against yellow fever virus (YFV). Participants who turn out positive on the YFV virus neutralization test will be retrospectively excluded from analyses, and replaced with new participants. Skin biopsy sampling (2X 4 mm punch biopsy) in the upper arm is performed only on the second visit, with additional microsampling (microbiopsy and wound blood sampling). The microbiopsy will be taken from 20 participants, followed by two skin punch biopsies from the upper arm from all participants. Subsequently, a blood swab will be collected from the wound blood from all participants.
- Conditions
- Yellow Fever (Healthy Volunteers), Biopsy/Methods
- Being tested
- Skin punch biopsy, Blood samples
- Medical subject headings
- Yellow Fever
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Skin punch biopsyProcedure or surgery
2 x 4mm skin punch biopsies in the upper arm will be taken from each participant at visit 2 with additional microsampling (microbiopsy and wound blood sampling)
Blood samplesProcedure or surgery
Blood sampling of 15 mL (10mL Lithium-Heparine + 5 mL SST) is performed on Visit 1 to confirm their vaccination status regarded to yellow fever
| Study group | Role | What they receive |
|---|---|---|
| Healthy unvaccinated participants against yellow fever virus | Other | Healthy participants that have not been vaccinated against yellow fever virus Receives: Procedure: Skin punch biopsy; Procedure: Blood samples |
What is being measured
The primary outcome is the main question the study is designed to answer.
Estimate the baseline number and proportion of skin-resident memory T cells against YFV (YFV-TRM) in the skin of unvaccinated and healthy volunteers against YFV
The number and proportion of YFV-specific T cells within the skin-resident lymphocyte parent population at visit 2, measured by flow cytometry.
Measured: Day 14 (Visit 2)
Secondary outcomes (1)
Estimate the baseline number and proportion of circulating effector- (YFV-TEM) and central-memory T cells against YFV (YFV-TCM) in the blood of unvaccinated and healthy volunteers against YFV
The number and proportion of circulating YFV-specific TCM and TEM cells within the CD3+ lymphocyte parent population at visit 1
Measured: Day 0 (Visit 1)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted9 Jun 2026
- Study start10 Aug 2026
- Primary completion15 Nov 2026 (estimated)
- Study completion15 Nov 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Yellow Fever (Healthy Volunteers)Studies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Other
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 40 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Institute of Tropical Medicine, Belgium
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07636551
- Sponsor's protocol ID
- 1966/25
- Status last verified
- Aug 2026
- First submitted
- 18 May 2026
- Last updated
- 13 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No