Trial reportVaccine2014
Re-examination of immune response and estimation of anti-Vi IgG protective threshold against typhoid fever-based on the efficacy trial of Vi conjugate in young children.
Trial report in Vaccine, 2014. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 18 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.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
18 citing papers in PubMed, 31 citations in OpenAlex.
- Safety and immunogenicity of a conjugate vaccine candidate against Salmonella enterica serovars Typhi and Paratyphi A in healthy adults in Europe: a phase 1 randomised controlled trial.The Lancet. Infectious diseases · 2026Trial
- Vi-specific serological correlates of protection for typhoid fever.The Journal of experimental medicine · 2021Trial
- Development and validation of immunological assays for preclinical evaluation of a novel bivalent typhoid conjugate vaccine.Human vaccines & immunotherapeutics · 2026Article
- Examining epidemiological models and economic analyses of typhoid conjugate vaccine: A scoping review.PLOS global public health · 2026Article
- Longevity of immune response after a single dose of typhoid conjugate vaccine against Salmonella Typhi among children in Hyderabad, Pakistan.International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases · 2024Article
- A strategic model for developing vaccines against neglected diseases: An example of industry collaboration for sustainable development.Human vaccines & immunotherapeutics · 2022Review
- Rotavirus spike protein ΔVP8* as a novel carrier protein for conjugate vaccine platform with demonstrated antigenic potential for use as bivalent vaccine.Scientific reports · 2021Article
- Article
- Cost effectiveness of typhoid vaccination in India.Vaccine · 2021Article
- Article
- Antibodies and Protection in SystemicInfection and immunity · 2020Review
- The need & the issues related to new-generation typhoid conjugate vaccines in India.The Indian journal of medical research · 2020Review
- Usefulness of the Serial Measurement of Vi Antibodies.Clinical infectious diseases : an official publication of the Infectious Diseases Society of America · 2018Article
- Use of a novel antigen expressing system to study the Salmonella enterica serovar Typhi protein recognition by T cells.PLoS neglected tropical diseases · 2017Article
- Cost-effectiveness analysis of typhoid conjugate vaccines in five endemic low- and middle-income settings.Vaccine · 2017Article
- Phase I clinical trial of O-acetylated pectin conjugate, a plant polysaccharide based typhoid vaccine.Vaccine · 2014Article
- Complex adaptive immunity to enteric fevers in humans: lessons learned and the path forward.Frontiers in immunology · 2014Review
- Vaccines against invasive Salmonella disease: current status and future directions.Human vaccines & immunotherapeutics · 2014Review
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
3 authors at 2 institutions in 1 country.
Funding
Abstract
backgroundThe capsular polysaccharide of Salmonella enterica serovar Typhi, Vi antigen, is an essential virulence factor and a protective antigen. Similar to other polysaccharide vaccines, the protective action of Vi, both to the polysaccharide alone or when presented as a conjugate, is mediated by serum IgG Vi antibodies. The evaluation of Vi capsular polysaccharide based vaccines to prevent typhoid fever would be significantly facilitated by the identification of a "protective level" of serum antibodies to Vi antigen.
methodsThe protective level of anti-Vi IgG against typhoid fever was derived from the protective efficacy and immune response of a Vi-rEPA conjugate vaccine efficacy trial. The estimation was derived by two methods: correlation of the percent efficacy and the antibody distribution profile in the vaccine group at a given period of observation, and use of the relative ratio of anti-Vi IgG levels between the vaccine and placebo groups greater or equal to the Relative Risk of typhoid fever used in the efficacy determination.
resultsBoth methods predicted a similar range of a minimum protective level of anti-Vi IgG between 1.4 and 2.0μg/ml (short term threshold). When applying a protective threshold of 10μg/ml at 6 months post immunization, an IgG level in excess of 1.4μg/ml was achieved by 90% of children at 46 months post immunization, consistent with an 89% level of protection over the duration of the study. We thus suggest that the proportion of children with Vi IgG>10μg/ml (long term threshold) 6 months after immunization may reflect the proportion protected over at least a 4 year period.
conclusionThe current assignment of an anti-Vi IgG protective level may be of value when evaluating vaccine performance of future Vi conjugate vaccines.
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What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.