View clinical trials related to Yellow Fever.
Filter by:No antiviral treatment exists for yellow fever, only supportive care, and therefore we rely on prevention through vaccination. Although this vaccine is very effective, stockpiles are insufficient in outbreak situations and some people have a contraindication to be vaccinated. For those who are unprotected and at risk of yellow fever infection, treatment could be life saving.
The goal of this clinical trial is to assess the immune response to the yellow fever vaccine 17D in adults with prior 17D vaccination. The main questions this study aims to answer are: - how does prior vaccination affect antibody responses to re-vaccination? - how does prior vaccination affect the immune cell response to re-vaccination? Participants will: - have been previously vaccinated with 17D. - be re-vaccinated with 17D. - provide medical and travel histories. - provide a blood sample prior to vaccination - provide a blood sample approximately every other day for 14 days after vaccination. - provide a blood sample approximately 28 days after vaccination. - complete a daily diary of symptoms following vaccination for 14 days. - report any additional symptoms after 14 days.
Northern Argentina is a risk area for yellow fever (YF). Recent studies have suggested that immunity wanes in children vaccinated between 9 and 23 months of age. In 2015, a collaborative study conducted by the Ministry of Health (MoH) of Argentina, the Pan American Health Organization (PAHO), and the US Centers for Disease Control and Prevention (CDC) assessed the immunogenicity and safety of co-administration of YF and MMR vaccines in a pediatric population at 12-13 months of age. A total of 741 children presenting for routine immunization at 12-13 months of age enrolled and completed the study. It is now four to seven years since this pediatric group received their YF vaccinations. This cohort is unique because their initial YF vaccination and immune response to the vaccine dose are well characterized. Contact information collected during the earlier study will be used to locate the children. If consent is obtained, a 5ml specimen of blood will be collected and shipped to the CDC's Arboviral Diseases Reference Laboratory (ADRL) in Fort Collins, CO for plaque reduction neutralization testing using a 50% cut-off (PRNT50) to detect YF virus-specific neutralizing antibodies. Children with neutralizing antibody titers that are higher than their baseline titer collected approximately 28 days following YF vaccination will have PRNTs done for cross-reacting flaviviruses.
We hypothesize that a high CD4+ and CD8+ T cell count will reduce viremia upon challenge with a structurally heterologous virus, and correspondingly result in reduced magnitude of host response to challenge infection. Primary Objective: To compare, after challenge with a structurally heterologous vaccine, the differences in levels of viremia between healthy adults who received primary vaccination with either YF17D vaccine, chimeric JE-YF17D vaccine, or inactivated JE vaccine. 58 subjects will be randomised into 1 of 2 arms (Arm B1 and Arm B2) in a 1:1 ratio, in a double-blind fashion. Subjects in Arm B1 will receive JE-YF17D vaccine (Imojev, Sanofi Pasteur) on Day 0 followed by YF17D vaccine (Stamaril, Sanofi Pasteur) on Day 28. Subjects in Arm B2 will receive Stamaril on Day 0 followed by Imojev on Day 28. Arm B3 will be conducted as a separate single-arm open label design in 14 subjects. Subjects in Arm B3 will receive inactivated JE vaccine (Ixiaro, Valneva) on Day 0 followed by Stamaril on Day 28. The rationale for these three study arms is as follows: Arm B1 will show the impact low levels of viremia, and the resultant low levels of virus-specific CD4+ and CD8+ T cells, would have on YF17D infection. In contrast, YF17D vaccination in Arm B2 would produce high levels of viremia, and in turn high levels virus-specific T cells, thus likely ameliorating JE-YF17D infection. Arm B3 will serve as the control arm, as vaccination with inactivated JE vaccine would not produce any YF17D-specific T cell response. Notably, the first vaccination in Arms B1 and B2 would also provide the viremia response in the absence of virus-specific T cells, which would serve as a reference point to interpret the outcome of the second vaccination.
ANRS 0146s NovaaTen study aims to determine the vaccine responses in the participants of the ANRS EP46 Novaa trial 10 years after a primary anti-yellow fever vaccination
The study is designed as a Phase III, double-blind, multi-center, randomized, active-controlled study in which four groups of participants (n=554 per group) will receive either one of three different manufacturing lots of SII-YFV or STAMARIL® - a licensed and WHO pre-qualified YFV.
The study is designed as a Phase III, double-blind, multicenter, randomized, active-controlled, parallel-group design in which two groups of participants will receive either SII-YFV or STAMARIL® - a licensed and WHO pre-qualified YFV. The study will start only after the approval from the applicable ethics committees and national regulatory agencies.
This is an open-label, randomized, exploratory study to evaluate the human immune response to reduced subcutaneous (SQ) dosing of Yellow Fever vaccine compared to the standard FDA approved subcutaneous vaccination dose. The current dose of the US FDA licensed Yellow Fever vaccine is approximately 55,000 plaque-forming unit(s) (PFU) in 0.5 mL administered SQ. Using the licensed dosage as standard, investigators are evaluating reduced doses of 1/5th (0.10 mL) and 1/10th (0.05 mL) Yellow Fever vaccine (YF-VAX).
This is a phase III trial on Children. The investigators will enroll a total of 750 participants in Fajikunda Health Center (Gambia) The aims of the study are - To describe the safety and immunogenicity of a booster dose of a licensed yellow fever vaccine administered to 3 different age cohorts of children, following a documented primary dose of a yellow fever vaccine administered at nine-months of age. - To characterise the rate of yellow-fever PRNT sero-reversion (seropositive to seronegative) over a period of 9 months to 8 years following a single primary dose of yellow fever vaccine administered to Gambian infants at nine months age. - To profile the immune response to the booster dose of YF vaccine in order to explore underlying mechanisms for longevity of vaccine-induced antibody.
This trial will be a randomized, placebo controlled, double-blind (within dosing group), dose escalation Phase 1 trial, evaluating dosages of 1 mcg and 5 mcg of HydroVax-002 YFV vaccine given intramuscularly on Day 1 and Day 29 in up to 25 healthy adults healthy adults ≥ 18 and < 50 years of age. The primary objective is to assess the safety, reactogenicity, and tolerability of the HydroVax-002 YFV vaccine administered intramuscularly in a two-dose series on Days 1 and 29 at a dose of 1 mcg or a dose of 5 mcg.