Validation of a yellow fever vaccine model using data from primary vaccination in children and adults, re-vaccination and dose-response in adults and studies with immunocompromised individuals.

Background: An effective yellow fever (YF) vaccine has been available since 1937. Nevertheless, questions regarding its use remain poorly understood, such as the ideal dose to confer immunity against the disease, the need for a booster dose, the optimal immunisation schedule for immunocompetent, immunosuppressed, and pediatric populations, among other issues. This work aims to demonstrate that computational tools can be used to simulate different scenarios regarding YF vaccination and the immune response of individuals to this vaccine, thus assisting the response of some of these open questions.

Duration of post-vaccination humoral immunity against yellow fever in children.

Introduction: Vaccination is the most important measure for prevention and control of yellow fever. It is recommended by the World Health Organization (WHO) for residents of endemic areas and travelers to risk areas. In 2013, the WHO discontinued the recommendation of booster doses every 10 years, indicating a single dose as sufficient for lifelong protection.

17DD Yellow Fever Revaccination and Heightened Long-Term Immunity in Populations of Disease-Endemic Areas, Brazil.

We evaluated the duration of neutralizing antibodies and the status of 17DD vaccine-specific T- and B-cell memory following primary and revaccination regimens for yellow fever (YF) in Brazil. We observed progressive decline of plaque-reduction neutralization test (PRNT) seropositivity and of the levels of effector memory CD4+ and CD8+ T cells, as well as interferon-γ+CD8+ T cells, 10 years after primary vaccination. Revaccination restored PRNT seropositivity as well as the levels of effector memory CD4+, CD8+, and interferon-γ+CD8+ T cells.

Yellow fever outbreak in Brazil: the puzzle of rapid viral spread and challenges for immunisation.

We discuss the complex eco-social factors involved in the puzzle of the unexpected rapid viral spread in the ongoing Brazilian yellow fever (YF) outbreak, which has increased the reurbanisation risk of a disease without urban cases in Brazil since 1942. Indeed, this rapid spatial viral dissemination to the Southeast and South regions, now circulating in the Atlantic Forest fragments close to peri-urban areas of the main Brazilian megalopolises (São Paulo and Rio de Janeiro) has led to an exponential increase in the number of yellow fever cases. In less than 18 months, 1,833 confirmed cases and 578 deaths were recorded most of them reported in the Southeast region (99,9%).

HIV cure: global overview of bNAbs' patents and related scientific publications.

Introduction: This article provides a global overview of patent deposits for broadly neutralizing antibodies (bNAbs), which have emerged as a key strategy for HIV cure and future HIV vaccines. Scientific and technological barriers to the discovery of an effective HIV vaccine in the last 40 years have raised concerns on the potential for relevant advances in this area. Nevertheless, recent breakthrough studies have identified novel immune pathways for new innovative HIV vaccine and HIV cure strategies.

Neonatal infections: Case definition and guidelines for data collection, analysis, and presentation of immunisation safety data.

Maternal vaccination is an important area of research and requires appropriate and internationally comparable definitions and safety standards. The GAIA group, part of the Brighton Collaboration was created with the mandate of proposing standardised definitions applicable to maternal vaccine research. This study proposes international definitions for neonatal infections.

Serious adverse events associated with yellow fever vaccine.

Yellow fever vaccine was considered one of the safest vaccines, but in recent years it was found that it could rarely cause invasive and disseminated disease in some otherwise healthy individuals, with high lethality. After extensive studies, although some risk factors have been identified, the real cause of causes of this serious adverse event are largely unknown, but findings point to individual host factors. Meningoencephalitis, once considered to happen only in children less than 6 months of age, has also been identified in older children and adults, but with good prognosis.

Immunogenicity and safety of measles-mumps-rubella vaccine delivered by disposable-syringe jet injector in healthy Brazilian infants: a randomized non-inferiority study.

This study aimed to determine if immunogenicity to measles-mumps-rubella vaccine delivered to infants via a disposable-syringe jet injector (DSJI) was non-inferior to that administered by needle and syringe (NS). Vaccination safety was evaluated, as were the use, performance, and acceptability of each delivery method. The DSJI was the PharmaJet 2009 generation-1 device (G1) and the vaccine was measles-mumps-rubella vaccine from Bio-Manguinhos.

Subdoses of 17DD yellow fever vaccine elicit equivalent virological/immunological kinetics timeline.

Background: The live attenuated 17DD Yellow Fever vaccine is one of the most successful prophylactic interventions for controlling disease expansion ever designed and utilized in larger scale. However, increase on worldwide vaccine demands and manufacturing restrictions urge for more detailed dose sparing studies. The establishment of complementary biomarkers in addition to PRNT and Viremia could support a secure decision-making regarding the use of 17DD YF vaccine subdoses.

17DD and 17D-213/77 yellow fever substrains trigger a balanced cytokine profile in primary vaccinated children.

Background: This study aimed to compare the cytokine-mediated immune response in children submitted to primary vaccination with the YF-17D-213/77 or YF-17DD yellow fever (YF) substrains.

Methods: A non-probabilistic sample of eighty healthy primary vaccinated (PV) children was selected on the basis of their previously known humoral immune response to the YF vaccines. The selected children were categorized according to their YF-neutralizing antibody titers (PRNT) and referred to as seroconverters (PV-PRNT(+)) or nonseroconverters (PV-PRNT(-)).

Cytokine signatures of innate and adaptive immunity in 17DD yellow fever vaccinated children and its association with the level of neutralizing antibody.

Background: The live attenuated yellow fever (YF) vaccines have been available for decades and are considered highly effective and one of the safest vaccines worldwide.

Methods: The impact of YF-17DD-antigens recall on cytokine profiles of YF-17DD-vaccinated children were characterized using short-term cultures of whole blood samples and single-cell flow cytometry. This study enrolled seroconverters and nonseroconverters after primovaccination (PV-PRNT⁺ and PV-PRNT⁻), seroconverters after revaccination (RV-PRNT⁺), and unvaccinated volunteers (UV-PRNT⁻).

Clinical and immunological insights on severe, adverse neurotropic and viscerotropic disease following 17D yellow fever vaccination.

Yellow fever (YF) vaccines (17D-204 and 17DD) are well tolerated and cause very low rates of severe adverse events (YEL-SAE), such as serious allergic reactions, neurotropic adverse diseases (YEL-AND), and viscerotropic diseases (YEL-AVD). Viral and host factors have been postulated to explain the basis of YEL-SAE. However, the mechanisms underlying the occurrence of YEL-SAE remain unknown.

Multicenter study on the immunogenicity and safety of two recombinant vaccines against hepatitis B.

The immunogenicity and safety of a new recombinant hepatitis B vaccine from the Instituto Butantan (Butang) were evaluated in a multicenter, double-blind, prospective equivalence study in three centers in Brazil. Engerix B was the standard vaccine. A total of 3937 subjects were recruited and 2754 (70%) met all protocol criteria at the end of the study.