Description of the Immune Response to Yellow Fever Vaccination (IVORY2)

Vaccine protection depends on a specific adaptive immune memory. However, a little-explored aspect of certain live vaccines may provide beneficial, non-specific protection against infections or pathogens other than the one from which the vaccine is derived. This is the concept of innate immune memory or " trained immunity", which differs from adaptive memory in its non-specificity. Innate immune memory is triggered by exposure to immunostimulants, and offers protection against unrelated pathogenic threats for several months or even years.

The project aims to carry out an exploratory study to observe, in the context of current practice, the immune response obtained after a subunit and a live attenuated vaccine

Study Overview

• Status: Recruiting
• Conditions: Infections; Immunization
• Intervention / Treatment: Biological: blood samples collection

Detailed Description

Vaccine protection depends on a specific adaptive immune memory. However, a little-explored aspect of certain live vaccines may provide beneficial, non-specific protection against infections or pathogens other than the one from which the vaccine is derived. This is the concept of innate immune memory or " trained immunity", which differs from adaptive memory in its non-specificity. Innate immune memory is triggered by exposure to immunostimulants, and offers protection against unrelated pathogenic threats for several months or even years.

For example, research has shown that the live attenuated BCG vaccine induce non-specific trained immunity, enabling innate immune cells to remember their first encounter and improve their immune status during a second confrontation with similar or different agents.

Other currently available live vaccines, such as BCG , could also "train" innate immune cells.

The project aims to carry out an exploratory study to observe, in the context of current practice, the immune response obtained after a subunit and a live attenuated vaccine

• Study Type: Interventional
• Enrollment (Estimated): 38
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Jessica Quintin, Dr; Phone Number: +33 144389454; Email: jessica.quintin@pasteur.fr
• Study Contact Backup: Name: Sandrine Fernandes Pellerin; Phone Number: +33 145688179; Email: sandrine.fernandes-pellerin@pasteur.fr

Study Locations

• France
  • Paris, France, 75015
    • Recruiting
    • Centre Médical de l'Institut Pasteur
    • Contact: Fabien TAIEB, Dr; Phone Number: +33 1 45 68 80 88; Email: fabien.taieb@pasteur.fr

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Age between 18 and 65
• Referred for immunisation against yellow fever and typhoid
• Any person with indication for the following vaccinations :
• Yellow fever
• Typhoïd
• Whose vaccination schedule includes two appointments 7 days apart
• Whose state of health is compatible with a single 51 ml blood sample collection
• Have consented to participate in the Ivory2 study
• Benefiting from a Social Security plan or equivalent

Exclusion Criteria:

• Anyone with a contraindication to yellow fever and/or typhoid vaccination.
• Any person who has been vaccinated against yellow fever and/or typhoid.
• Anyone who has lived in an endemic area (≥ 1 year) and/or has a history of Typhoid.
• Anyone who is unable to attend the visit 1-month after the typhoid vaccine injection.
• Women claiming to be pregnant or breast-feeding
• Anyone unable to give informed consent for participation

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Other: People with an indication for primary immunization against yellow fever and typhoid; People with an indication for primary immunization against yellow fever and typhoid and whose vaccination schedule includes two appointments 7 days apart	Biological: blood samples collection; blood samples collected at D0 ,W1, W5, M3 and M6

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Immunological profile of PBMCs, before and after yellow fever vaccination	Cytokine production assays (e.g. TNFa, IL6, IL1b)	6 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Description of the response to TyphimVi® vaccine	ELISA-based quantification of Anti-Vi antibody level >30 U/mL at week 5, and/or fold increase ≥2 compared with pre-vaccination IgG titer.	6 months

Collaborators and Investigators

• Sponsor: Institut Pasteur
• Investigators: Principal Investigator: Fabien Taieb, Dr, Institut Pasteur

Study record dates

Study Major Dates

• Study Start (Actual): September 30, 2024
• Primary Completion (Estimated): April 30, 2026
• Study Completion (Estimated): April 30, 2027

Study Registration Dates

• First Submitted: November 29, 2024
• First Submitted That Met QC Criteria: December 4, 2024
• First Posted (Actual): December 5, 2024

Study Record Updates

• Last Update Posted (Actual): June 29, 2025
• Last Update Submitted That Met QC Criteria: June 27, 2025
• Last Verified: June 1, 2025

More Information

Terms related to this study

• Keywords: immunology; Vaccine response
• Additional Relevant MeSH Terms: Vector Borne Diseases; Mosquito-Borne Diseases; Infections; RNA Virus Infections; Virus Diseases; Arbovirus Infections; Flavivirus Infections; Flaviviridae Infections; Hemorrhagic Fevers, Viral; Yellow Fever
• Other Study ID Numbers: 2023-149

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No