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Understanding How Vaccines Create Lasting Protection

This study aims to understand why some vaccines, like the Yellow Fever 17D Vaccine, offer long-lasting protection, while others, such as the Quadrivalent seasonal influenza vaccine, do not. Researchers will give participants either the Yellow Fever 17D Vaccine or the Quadrivalent seasonal influenza vaccine. They will then collect blood samples to measure the strength of your immune response (how well your body fights off infection) for up to 270 days after vaccination. This will help them learn more about what makes a vaccine's protection durable. The study is looking for 66 participants between 18 and 50 years old. The current recruitment status is unclear.

Study design
This interventional study plans to enroll 66 participants. It will compare the immune responses to two different vaccines.
What's involved
You would receive either the Yellow Fever 17D Vaccine or the Quadrivalent seasonal influenza vaccine. You would also have blood samples collected at various times.
Compensation
Not stated in the trial record.
Follow-up
Your immune response will be measured for up to 270 days after vaccination.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT05801978

Durability of Vaccine Responses

Recruiting
PHASE4Ages 18–50InterventionalBasic science
Emory University
~66 participants
Updated 2026-07-17 on ClinicalTrials.gov
What's tested:Live Attenuated Yellow Fever 17D VaccineQuadrivalent seasonal influenza vaccine

At a glance

Recruiting sites
3 of 3 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Magnitude of neutralizing antibody (nAB) response against YF-17D in blood
Measured over Up to 270 days after vaccination
+1 more outcome measured

Conditions

Vaccine Response

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Healthy Volunteers

NCT05801978

Where you'd take part

This study runs at 3 sites. They're the same protocol — you choose where, and that choice sets who your contact draft is addressed to.

  • Emory University Hospital

    Atlanta, Georgiastudy coordinator listed

    Recruiting

  • Emory Winship Cancer Institute

    Atlanta, Georgiastudy coordinator listed

    Recruiting

  • The Hope Clinic of Emory University

    Decatur, Georgiastudy coordinator listed

    Recruiting

Sites open and close at different times, so the status above is per site — it can differ from the study's overall status.

Study leadership

  • Nadine Rouphael, MD · PRINCIPAL_INVESTIGATOR · Emory University

Who to contact

Nadine Rouphael, MD
[email protected]
404-712-1435
Email the study team

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Eligibility criteria

Inclusion

Able to understand and give informed consent.
Age 18-50 years.
Participants agree not to take any live vaccines 30 days before or after (14 days for inactivated) vaccination.
Women of child bearing potential must agree to use effective birth control for the first 3 months of the study. A negative urine pregnancy test must be documented prior to vaccination and prior to tissue sampling procedures.

Exclusion

History of allergy or serious adverse reaction, including Guillain-Barré syndrome, to a vaccine or vaccine products.
History of a medical condition resulting in impaired immunity (such as HIV infection, cancer, particularly leukemia, lymphoma, use of immunosuppressive or antineoplastic drugs or X-ray treatment). Persons with previous skin cancers or cured non-lymphatic tumors are not excluded from the study.
History of Hepatitis B or Hepatitis C infection.
Chronic clinically significant medical problems that could affect the immune response, require medication that would affect the immune response, or have signs or symptoms that could be confused with reactions to vaccination, including (but not limited to):
Thymus gland problems (such as myasthenia gravis, DiGeorge syndrome, thymoma) or removal of thymus gland or history of uncontrolled autoimmune disorder.
Pregnancy or breast feeding, or plans to become pregnant in the first 3 months of study participation.
Receipt of blood products or immune globulin product within the prior 3 months.
Active duty military.
History of excessive alcohol consumption, drug use, psychiatric conditions, social conditions or occupational conditions that in the opinion of the investigator would preclude compliance with the trial.
History of previous yellow fever, West Nile, Dengue, St. Louis encephalitis, or Japanese encephalitis vaccination or infection.
Previous residence in a country where there is a risk of yellow fever virus (YFV) transmission
History of allergy to eggs, chicken, or gelatin.
History of influenza infection within the same influenza season.

What this trial measures

  • Magnitude of neutralizing antibody (nAB) response against YF-17D in bloodUp to 270 days after vaccination

    Magnitude of neutralizing antibody responses against YF-17D at 270 days after vaccination among participants who receive YF-17D.

  • Magnitude of neutralizing antibody (nAb) response against QIV in bloodUp to 270 days after vaccination

    Magnitude of neutralizing antibody responses against influenza vaccine strains at 270 days after vaccination among participants who receive QIV.