Trial reportPLoS neglected tropical diseases2025
Immunogenicity of a single dose of the 17DD yellow fever vaccine in a cohort of adults and children in a non-endemic area, and its association with dengue and Zika seropositivity.
Trial report in PLoS neglected tropical diseases, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT07527247 (Using AS01 Adjuvant to Improve Immune Response in Older Adults Through Trained Immunity), which is not on this map. Cited by 2 papers.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Using AS01 Adjuvant to Improve Immune Response in Older Adults Through Trained Immunity
Who cites it
2 citing papers in PubMed.
- A cohort study of the duration of immunity to yellow fever after 4 years of primary vaccination in children and adults.Transactions of the Royal Society of Tropical Medicine and Hygiene · 2026Article
- Reemergence of yellow fever virus in forest and periurban settings in Brazil.Communications medicine · 2025Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
24 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
In 2013, the World Health Organization (WHO) withdrew the recommendation of booster doses of the yellow fever (YF) vaccine, based on retrospective and cross-sectional studies that showed lifelong protective immunity from a single dose. Currently, yellow fever transmission in Brazil occurs only through the jungle (sylvatic) cycle. However, the high vector density of Aedes aegypti, which transmits other orthoflaviviruses, is a concern for the expansion of YF in other regions of the country. We conducted a cohort study to assess the duration of vaccine-induced immunity in adults and children residing in an area without wild-type YF virus circulation but with a high incidence of other orthoflaviviruses. This phase IV, uncontrolled cohort study was conducted in three municipalities in northeastern Brazil. The 17DD strain vaccine was administered to children aged 9 months to 4 years and adults aged 18 to 50 years. Blood samples for antibody titration were collected before vaccination, 30-45 days after, and one year after vaccination. The following assays were used: µFRNT for yellow fever and dengue; PRNT for Zika; and chemiluminescence for Zika (IgG and IgM) and dengue (IgG). YF seroconversion rates 30-45 days post-vaccination increased with age, reaching 99% in adults, while 10% of infants remained without detectable antibodies. Seropositivity for dengue neutralizing antibodies was inversely associated with YF antibody titers 30-45 days post-vaccination. Previous Zika infection showed no substantial association with YF antibody titers post-vaccination. One year after vaccination, a considerable reduction in YF antibody titers was observed across all age groups, regardless of prior dengue or Zika infections. Our data support the Brazilian National Immunization Program's recommendation for a booster dose of the vaccine at 4 years of age. Current recommendations assuming lifelong protection from a single dose of the YF vaccine do not appear to provide sufficient protection in high-risk areas, particularly where infants are the primary target for vaccination.
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