View clinical trials related to Yellow Fever.
Filter by:Epidemic viral diseases have become more prevalent in recent years. Among the various strategies to prevent such epidemics, vaccination is the most cost-effective. However, populations that are immunized are typically already exposed to multiple previous vaccinations or natural infections. Studies from this and other laboratories have revealed that pre-existing dengue antibodies can either inhibit or enhance subsequent dengue infection depending on the pre-existing antibody levels. While cross-reactive antibody is potentially pathogenic in dengue, how it impacts immune response to vaccination is unclear. Indeed, aggregated at the site of vaccination and the respective draining lymph nodes are antigen-presenting and immune regulatory cells that express Fc receptors and play pivotal roles in determining the magnitude and polarity of the immune response. Vaccine uptake by these antigen-presenting cells may thus be either inhibited or enhanced when vaccines are opsonized with cross-reactive antibodies. In view of the limited knowledge on how cross-reactive antibodies affect vaccination outcome, investigators propose here a study that exploits the known cross reactivity between Japanese encephalitis (JE) virus antibody and yellow fever (YF) vaccine. Investigators hypothesize that cross-reactive antibodies impacts antibody response to YF at the point vaccination in a concentration-dependent manner by altering both vaccine uptake and the innate immune response by antigen presenting cells. Investigators will structure an open label clinical trial on sequential vaccination with JE and YF vaccines, with different time intervals between vaccinations. This would test immune response to YF vaccination in subjects with different titer of cross-reactive JE vaccine-derived antibodies.
It is thought that vaccines trigger innate inflammatory responses to induce antigenspecific adaptive immunity (the desired effect), but excessive inflammation may lead to serious inflammatory complications or unwanted side effects. Currently there is a lack of reliable biomarkers (a measurable biological response that predicts something) able to predict severe inflammation and this has resulted in the development of several vaccines being terminated and the withdrawal of some licensed vaccines which were associated with inflammatory complications. This study is part of the BIOVACSAFE project which is a 5year €30M project funded by the Innovative Medicine Initiative. The project involves a series of clinical studies using licensed vaccines as benchmarks to generate clinical data on inflammation and identify biomarkers that can be used to predict acceptable reactogenicity. The target is to identify biomarkers that can predict the occurrence of beneficial and detrimental effects in response to a vaccine. Such biomarkers could be used in future vaccine development programs to optimize selection of vaccine candidates with a profile that will be unlikely to generate worrisome safety signals once they are in generalized use. This study is one in a series of "training" studies which will each use different licensed vaccines that are prototypical representatives of a class of vaccine used in a particular target population. Forty eight subjects will be randomised into three groups to receive: A) Varicella zoster vaccine (n = 20), B) Yellow Fever vaccine (n = 20), C) Saline placebo (n = 8). Following a screening visit, participants will undergo a seven day residential visit which will include immunization and intensive monitoring of physiological (e.g. heart rate, oral temperature, blood pressure) metabolic and immune (innate and adaptive) parameters. This visit will be followed up by four outpatient visits with further monitoring and blood samples.
The aim of this study was to evaluate the administration of CYD dengue vaccine serotypes (1, 2, 3 and 4) following a compressed schedule in 3 different populations. Primary Objectives: - To describe the humoral immune response to each of the 4 parental dengue virus serotypes at baseline and 28 days after CYD dengue vaccine Dose 3 in Group 1 (Month [M] 13) and Group 2 (M07), irrespective of whether or not Yellow Fever (YF) vaccine has been previously administered. - To describe the persistence of the humoral immune response to each of the 4 parental dengue virus serotypes 6 months after CYD dengue vaccine Dose 3 in Group 1 (M18) and Group 2 (M12), irrespective of whether or not YF vaccine has been previously administered. Secondary Objective: - To describe the humoral immune response to each of the 4 parental dengue virus serotypes at baseline and 28 days after CYD dengue vaccine Dose 1 and Dose 2 in Groups 1 and 2, irrespective of whether or not YF vaccine has been previously administered. - To describe the humoral immune response to each of the 4 parental dengue virus serotypes at baseline and 28 days after CYD dengue Dose 1 in the combined YF-participants in Group 1 (N=60) and Group 2 (N=60), and in Group 3 (N=120). - To describe by FV status at baseline the humoral immune response to each of the 4 parental dengue virus serotypes at baseline and 28 days after each injection of CYD dengue vaccine in Groups 1, 2, and 3. - To describe the safety profile after each injection of CYD dengue vaccine and/or YF vaccine.
This study compares the safety and immunogenicity profile of several travel vaccines given alone or concomitantly with MenACWY-CRM to healthy adults.
The study was designed to evaluate whether the first CYD dengue vaccination can be administered concomitantly with Stamaril® yellow fever vaccine during the same day and visit, but at 2 different sites of administration. Primary Objective: - To demonstrate the non-inferiority of the immune response against Yellow Fever (YF) in flavivirus (FV) non-immune subjects at baseline receiving one dose of Stamaril vaccine administered concomitantly with the first dose of CYD dengue vaccine compared to participants receiving one dose of Stamaril vaccine concomitantly with placebo. Secondary Objectives: - To assess the non-inferiority of YF immune response 28 days post-Stamaril vaccination based on seroconversion rates regardless of the FV status of participants at baseline. - To describe the YF immune response 28 days post-Stamaril vaccination in both groups. - To describe the antibody (Ab) response to each dengue virus serotype 28 days post CYD dengue vaccine (Visit [V] 05 and V07), following CYD dengue vaccine Dose 1 and Dose 2 from Group 2 versus following CYD dengue vaccine Dose 2 and Dose 3 for Group 1 (effect of YF vaccination). - To describe the safety of Stamaril vaccine administered concomitantly with the first dose of CYD dengue vaccine, or Stamaril administered concomitantly with placebo. - To describe the safety of CYD dengue vaccine after the first dose of CYD dengue vaccine administered concomitantly with Stamaril vaccine or CYD vaccine administered alone. - To describe the safety of the CYD dengue vaccine in all participants after each dose.
Main objective : To develop the tools for evaluation of humoral and cell-mediated immunity after Yellow Fever Vaccine (YFV) and compare virological and immune responses in HIV-positive and HIV-negative individuals who had not been given YFV before. Secondary objectives : - To develop and assess ELISPOT technology for yellow fever and to measure the response within 7, 14, 28, 90 and 365 days of administration of YFV in 30 HIV negative subjects and 40 HIV positive subjects (CD4 > 350/mm3 under Highly Active Antiretroviral Therapy (HAART) for at least one year, with a viral load < 50 copies/mL since at least 6 months) in terms of : (1) seroconversion by fluorescence, (2) cytotoxic response in ELISPOT, (3) neutralizing antibody levels in Plaque reduction neutralization test (PRNT:reference method) and a new pseudotype based method, (4) post-vaccination viremia and (5) diversity of viral quasi-species. - To assess the impact of YFV on the T-lymphocyte response against HIV by ELISPOT and viral load.
The yellow fever vaccine is a live, attenuated virus that results in a robust immune response, especially in the T cell compartment. The researchers have been studying immune responses to live viral infections using the yellow fever vaccine as a model for a live viral infection. In this study, the researchers are interested in looking at the processing and lifespan of yellow fever specific CD8 T cell by measuring DNA replication and cell proliferation in humans using a naturally occurring stable isotope called deuterium.
The objective of this study is to study immune memory generated against the yellow fever (YFV) vaccine in participants who have previously received the vaccine. Volunteers will not receive vaccine shots; only immune responses to previous yellow fever vaccination will be studied. The study involves one or multiple blood draws.
The Phase 1 trial is a single-center, randomized, double blind, placebo-controlled, dose-ranging out-patient study designed to provide the first clinical data on the safety, tolerability and immunogenicity of XRX-001 inactivated yellow fever vaccine in 60 healthy male and female volunteers, 18-49 years of age. Subjects will receive two inoculations of one of two dose levels of XRX-001 vaccine. A control group will receive placebo. Safety will be determined by the incidence and severity of adverse events in each treatment group and in the combined cohorts in the double blind treatment period up to 42 days post-vaccination. Subjects will also be followed-up at 3, 6 and 12 months to determine severe adverse events (SAEs) and changes in health status. Efficacy will be assessed by neutralizing antibody response to the vaccine. The co-primary immunogenicity endpoints will be the dose-response analysis of seroconversion rates (fourfold or greater increase in neutralizing antibody titer between baseline and Day 42) and of the 50% plaque reduction neutralization test (PRNT50) geometric mean titers (GMT) at Day 42. Secondary immunogenicity endpoints will include: 1. The seroconversion rates and GMT neutralizing antibody titers for all dose groups combined on Days 21 and 42. 2. The reverse cumulative distribution curve of antibody titers on Days 21 and 42 for each dose group and for all dose groups combined 3. The duration of antibody titers displaying the seroconversion rate and GMT across all time-points to Month 12, by treatment group and for both dose groups combined.
The purpose of this study is to obtain safety, tolerability, and immunogenicity data on the co-administration or sequential administration of Chimeravax™-JE vaccine and STAMARIL®. Objectives: Safety: - Obtain safety and tolerability data of a single, fixed dose of ChimeriVax™-JE administered concurrently, one month before or one month after STAMARIL® to adult volunteers (≥ 18 to ≤ 55 years) without prior Japanese encephalitis (JE) or yellow fever (YF) vaccination. Immunogenicity: - Obtain data on the antibody response to a single, fixed dose of ChimeriVax™-JE administered concurrently, one month before or one month after STAMARIL® to adult volunteers without prior JE (or YF) vaccination. - Assess the durability of the immune response in adult volunteers 6 months after administration of ChimeriVax™-JE and STAMARIL®.