Yellow Fever Vaccine Clinical Trial
Official title:
Clinical Study of Immunity Duration of Yellow Fever Vaccine in Military, Participants of "Dose-response Study of Yellow Fever Vaccine 17DD Produced by Bio-Manguinhos / Fiocruz" in 2009
Yellow fever is an acute viral disease transmitted by mosquitoes in South America, Central
America and Africa. It is more prevalente in males gender and the age above 15 years due to
the greater exposure in the wild endemic area of yellow fever.
According to the World Health Organization (WHO), 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 issue 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, many studies have demonstrated a reduction of the antibody titrer over
the years. Consequently, there is more concern about people who live in endemic areas. For
this reason, Brazil recommends revaccinating once at least until additional studies are
performed.
It is important to know the duration of immunity induced by lower doses of YF vaccine. In our
knowledge, there is a lack of clinical studies evaluating the immunity duration of the yellow
fever vaccine with lower doses. This information is relevant to subsidize the routine
recommendation of YF vaccine fractional dose for adults.
This is an observational study in young adult males 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. ;
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