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.

Study Overview

Status

Unknown

Detailed Description

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.

Study Type

Observational

Enrollment (Anticipated)

255

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

    • RJ
      • Rio De Janeiro, RJ, Brazil, 21040-900
        • Recruiting
        • Unidade de Ensaios Clínicos em Imunobiológicos / Instituto de Tecnologia em Imunobiológicos de Bio-Manguinhos / Fiocruz
        • Contact:
        • Contact:
        • Principal Investigator:
          • Akira Homma
        • Sub-Investigator:
          • Maria de Lourdes de Sousa Maia

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (ADULT, OLDER_ADULT)

Accepts Healthy Volunteers

N/A

Genders Eligible for Study

Male

Sampling Method

Non-Probability Sample

Study Population

Participants will be healthy male adults who received the first dose of the yellow fever vaccine in 2009 when they participated in the "Dose-response study of the yellow fever vaccine 17DD produced by Bio-Manguinhos / Fiocruz".

Participation in the study will be documented at the time of signing the Informed Consent Form.

Description

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).

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Number of individuals who were protected 10 years after the first dose of the yellow fever vaccine, assessed by the neutralization test
Time Frame: 10 years after the first dose of yellow fever vaccine
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

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Collaborators

Investigators

  • Principal Investigator: Akira Homma, Instituto de Tecnologia em Imunobiológicos Bio-Manguinhos / FIOCRUZ

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (ACTUAL)

April 8, 2019

Primary Completion (ANTICIPATED)

August 31, 2020

Study Completion (ANTICIPATED)

August 31, 2020

Study Registration Dates

First Submitted

May 21, 2020

First Submitted That Met QC Criteria

June 1, 2020

First Posted (ACTUAL)

June 4, 2020

Study Record Updates

Last Update Posted (ACTUAL)

June 4, 2020

Last Update Submitted That Met QC Criteria

June 1, 2020

Last Verified

May 1, 2020

More Information

Terms related to this study

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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