Duration of Immunity 10 Years After a Dose-response Study With Yellow Fever Vaccine

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

Get a concise snapshot of the trial, including recruitment status, study phase, enrollment targets, and key timeline milestones.

Recruitment Status

UNKNOWN

Total Enrollment

255 participants

Study Classification

OBSERVATIONAL

Study Start Date

2019-04-08

Study Completion Date

2020-08-31

Brief Summary

Review the sponsor-provided synopsis that highlights what the study is about and why it is being conducted.

Yellow fever is an acute febrile infectious disease transmitted to man urban cycle by mosquitoes infected by an arbovirus of the genus Flavivirus family Flaviviridae. Its occurrence is recorded in South America Central America and Africa. In cities the yellow fever vector is the Aedes aegypti mosquito which also transmits dengue viruses zika and chikungunya. This disease is more frequent in males and the most affected age group is above fifteen years due to the greater exposure related to the penetration in wild areas of the endemic zone of yellow fever. Another risk group is unvaccinated people who live near wild environments where the virus circulates. According to the World Health Organization a single dose of the yellow fever vaccine is sufficient to maintain protective immunity against yellow fever for a lifetime therefore a booster dose is not required. This question is difficult to evaluate because there is no serological correlate of protection against yellow fever and seropositivity is defined with several cut off points. Although studies indicate that the duration of protection after vaccination is long there is considerable evidence in the literature that antibody titer falls over the years reaching levels considered as seronegative in at least a portion of the vaccinees. This is of more concern to people living in endemic areas who are exposed to the virus throughout their lives. For this reason Brazil recommended revaccinating once at least until additional studies were done. The need to increase Bio Manguinhos production capacity to meet the increased demand from Brazil and other countries is urgent. The occurrence of epidemics when millions of individuals need to be vaccinated in a short period of time exceeds production capacity and this is a recurrent problem. The current vaccine has a very high potency well above the thousand international units recommended by World Health Organization. But we need to generate additional evidence that very low doses of viral particles in the yellow fever vaccine are still immunogenic and that their immunogenicity can be maintained for at least ten years after vaccination. This evidence will support the rapid increase of their availability by the fractionation of doses or other alternatives.

Related Clinical Trials

Explore similar clinical trials based on study characteristics and research focus.

Clinical Study of Immunity Duration of Yellow Fever Vaccine in Military

NCT03338231

Yellow Fever Vaccine

COMPLETED

Immunity Period After One Dose of Yellow Fever Vaccine in Adults and Children (Paraiba Study)

NCT02555072

Yellow Fever Vaccine Immunity

ACTIVE_NOT_RECRUITING PHASE4

Phase III Trial to Evaluate Efficacy and Safety of a Tetravalent Dengue Vaccine

NCT02406729

Dengue

ACTIVE_NOT_RECRUITING PHASE3

Study on the Persistence of Zika Virus (ZIKV) in Body Fluids of Patients With ZIKV Infection in Brazil

NCT03106714

Zika Virus

COMPLETED

Virological and Immunological Determinants of Arbovirus Infection in New Caledonia

NCT04619823

Arbovirus Infections Zika Dengue +1 more

RECRUITING NA

Detailed Description

Dive into the extended narrative that explains the scientific background, objectives, and procedures in greater depth.

This is an observational study in young adult males who received the first dose of the yellow fever vaccine when they participated in the Dose response study of the yellow fever vaccine produced by Bio Manguinhos Fiocruz. The purpose of this study is to know whether reduced dose immunity is maintained for at least ten years. This information is crucial to support the recommendation to use fractional dose in adults a topic of great interest to World Health Organization.

Conditions

See the medical conditions and disease areas that this research is targeting or investigating.

Yellow Fever Vaccine

Study Design

Understand how the trial is structured, including allocation methods, masking strategies, primary purpose, and other design elements.

Observational Model Type

COHORT

Study Time Perspective

OTHER

Eligibility Criteria

Check the participation requirements, including inclusion and exclusion rules, age limits, and whether healthy volunteers are accepted.

Inclusion Criteria

* Have participated as a volunteer of the study carried out in 2009.
* Seronegative volunteers before vaccination in the study "Dose-response study of yellow fever vaccine 17DD produced by Bio-Manguinhos / Fiocruz" carried out in 2009. Non-revaccinated volunteers, seropositive in the study "Duration of immunity to yellow fever in volunteers eight years after a dose-response study", conducted in 2017.
* Not having received another yellow fever vaccine after participating in the study "Dose-response study of the yellow fever vaccine produced by Bio-Manguinhos / Fiocruz" carried out in 2009 and the study "Duration of immunity to yellow fever in volunteers eight years after a dose-response study", conducted in 2017.
* Available to follow up during the field study period.
* Agree to give name, address, phone, and other contact information, if necessary.
* Agree to strictly follow the study protocol.
* Able to understand and sign the Informed Consent Form (ICF).
* Understand the impossibility of participating in another clinical trial during the time of participation in this study.

Note: Individuals with a history of travel to areas endemic for yellow fever may be included but will be analyzed separately.