Yellow Fever Vaccine Clinical Trial
Official title:
Duration of Immunity 10 Years After a Dose-response Study With Yellow Fever Vaccine - Complementary Study
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.
| Status | Recruiting |
| Enrollment | 255 |
| Est. completion date | August 31, 2020 |
| Est. primary completion date | August 31, 2020 |
| Accepts healthy volunteers | |
| Gender | Male |
| Age group | 18 Years and older |
| Eligibility |
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. Exclusion Criteria: - Refusal to collect biological material (blood). |
| Country | Name | City | State |
|---|---|---|---|
| Brazil | Unidade de Ensaios Clínicos em Imunobiológicos / Instituto de Tecnologia em Imunobiológicos de Bio-Manguinhos / Fiocruz | Rio De Janeiro | RJ |
| Lead Sponsor | Collaborator |
|---|---|
| The Immunobiological Technology Institute (Bio-Manguinhos) / Oswaldo Cruz Foundation (Fiocruz) | Wellcome Trust |
Brazil,
| Type | Measure | Description | Time frame | Safety issue |
|---|---|---|---|---|
| Primary | Number of individuals who were protected 10 years after the first dose of the yellow fever vaccine, assessed by the neutralization test | Serological status of yellow fever in adult individuals 10 years after seroconversion in a low dose or full dose study of the 17DD yellow fever vaccine produced by Bio-Manguinhos / Fiocruz. | 10 years after the first dose of yellow fever vaccine |
| Status | Clinical Trial | Phase | |
|---|---|---|---|
| Enrolling by invitation |
NCT01244802 -
Characterization of Human Memory Immune Responses to Prior Yellow Fever Vaccination
|
||
| Completed |
NCT03116802 -
Yellow Fever Vaccine on Statin/ Non Statin Subjects
|
Phase 2 | |
| Completed |
NCT03338231 -
Clinical Study of Immunity Duration of Yellow Fever Vaccine in Military
|
N/A | |
| Active, not recruiting |
NCT03591003 -
"Persistence of Neutralizing Antibodies Against Yellow Fever (YF) in HIV-infected Patients"
|
||
| Active, not recruiting |
NCT02555072 -
Immunity Period After One Dose of Yellow Fever Vaccine in Adults and Children (Paraiba Study)
|
Phase 4 |