In short
Clinical trials are studying YELLOW FEVER VIRUS STRAIN 17D-204 (LIVE, ATTENUATED) to see how well yellow fever vaccination works and how the immune system responds. The trials include adults and compare different vaccine routes or compare an investigational vaccine with a control vaccine. They mainly measure immune response and skin immune cells after vaccination.
Key points
- Clinical trials of YELLOW FEVER VIRUS STRAIN 17D-204 (LIVE, ATTENUATED) are studying yellow fever vaccination in adults. One Phase 3 trial compares intradermal, subcutaneous, and intramuscular vaccination routes and measures skin immune cells at day 28. Another Phase 2 trial in adults in Europe and Asia compares an investigational yellow fever vaccine with Stamaril and measures seroconversion after 28 days. Both studies are authorised and focus on immune response rather than treatment of disease.
Trial overview
The clinical trials in this set are studying YELLOW FEVER VIRUS STRAIN 17D-204 (LIVE, ATTENUATED) through yellow fever vaccination research. Both studies are interventional studies, which means researchers give a vaccine and then measure what happens after vaccination.
All listed trials are authorised and focus on immune response after vaccination, not on treating active yellow fever disease.
Phase 3 study of vaccination route
One Phase 3 trial compares three vaccination routes: intradermal, subcutaneous, and intramuscular. The study uses STAMARIL and includes 222 participants.
This trial asks whether the way the vaccine is given changes the immune response in the skin. The brief summary says the study compares the number and proportion of skin-resident memory T cells against yellow fever virus at day 28 after vaccination.
The trial includes three vaccine routes: 0.5 ml intramuscular injection, 0.1 ml intradermal use, and 0.5 ml subcutaneous injection. These details matter because the study is trying to see whether route affects the immune result.
Phase 2 comparison study in adults
Another trial is a Phase 2 study in adults in Europe and Asia, with an enrollment of 690 participants. It compares an investigational yellow fever vaccine, called vYF, with the control vaccine STAMARIL.
The main goal is to show non-inferiority, which means the investigational vaccine should not perform worse than the control vaccine by more than an allowed amount. The study looks at the antibody response 28 days after one dose given on Day 01.
The primary outcome is the percentage of participants in an EU group who have seroconversion in a yellow fever virus-naïve population. In this trial, seroconversion is defined as a 4-fold rise in neutralizing antibody levels compared with the level before vaccination.
Outcomes and endpoints
These studies mainly measure immune markers, not symptoms or disease cure. In the Phase 3 study, the primary outcomes are the percentage and the absolute number of YFV-specific T cells within the skin-resident lymphocyte parent population at day 28, measured by flow cytometry.
In the Phase 2 study, the primary outcome is the seroconversion rate in yellow fever virus-naïve participants after vaccination. This endpoint is used to judge how strongly the body responds to the vaccine.
Who the studies include
The available data show that both trials are focused on adults. One study includes adults in Europe and Asia, while the other compares vaccine routes in a larger group of 222 participants.
The Phase 2 study specifically mentions a yellow fever virus-naïve population, which means participants who have not previously had a yellow fever virus immune response before the study. This helps researchers measure the response to the study vaccine more clearly.
What the results mean
These trials are designed to help researchers understand whether different vaccination routes or different vaccine products lead to a strong immune response. The Phase 3 study looks at immune cells in the skin, while the Phase 2 study looks at antibody response in blood.
Because the studies are authorised and still focused on immune outcomes, they are part of the research process that helps compare vaccination strategies for yellow fever prevention.