NCT04416477

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

Status unknown Last updated 4 June 2020

What this trial tests

trial in Yellow Fever Vaccine in 255 participants. Status unknown.

Timeline

8 April 2019

Primary endpoint
31 August 2020

31 August 2020

Quick facts

Lead sponsor	The Immunobiological Technology Institute (Bio-Manguinhos) / Oswaldo Cruz Foundation (Fiocruz)
Status	Status unknown
Study type	OBSERVATIONAL
Enrollment	255
Start date	8 April 2019
Primary completion	31 August 2020
Estimated completion	31 August 2020
Sites	1 location across Brazil

Conditions studied

• Yellow Fever Vaccine — all drugs for Yellow Fever Vaccine →

Sponsor

The Immunobiological Technology Institute (Bio-Manguinhos) / Oswaldo Cruz Foundation (Fiocruz)

Who can join

18 and older, male only, with Yellow Fever Vaccine. Patients with the condition only — healthy volunteers not accepted.

Sponsor's own description

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.

Publications & conference data

1 peer-reviewed publication reference this trial (live from Europe PMC):

1. Duration of post-vaccination immunity to yellow fever in volunteers ten years after a dose-response study - A complementary study.
   Vianna CM, Noronha TG, Camacho LAB, Andrade RC, et al · · 2024 · cited 5× · PMID 38926068 · DOI 10.1016/j.vaccine.2024.06.050