NCT05108818 · University of Pennsylvania
Characterization of Humoral and Cellular Immune Responses Elicited by Influenza Vaccination in Healthy Adults
What this study is about
Cellular and humoral immune responses before and after seasonal influenza vaccination will be assessed. Each year, up to 100 participants will be enrolled. To study age-specific differences in immune responses, participants with various years of birth will be enrolled.
View original scientific description
Cellular and humoral immune responses before and after seasonal influenza vaccination will be assessed. Each year, up to 100 participants will be enrolled. To study age-specific differences in immune responses, participants with various years of birth will be enrolled. The investigators hypothesize that humans with different birth years will mount antibody and cellular responses of different specificities following seasonal influenza vaccination.
Interventions
BIOLOGICAL
Seasonal influenza vaccine
The seasonal influenza vaccine is administered intramuscularly at a dose of 15 ug of HA per component, as approved by the FDA.
Primary outcome measures
Effect of year of birth on neutralizing antibody titers elicited by influenza vaccination
Time frame: 7 years
Because year of birth can be used to predict the influenza viruses circulating during the first years of life, assessing antibody responses in individuals of different birth years is one way of determining how prior exposure affects immune responses to seasonal influenza vaccination and infection. The investigators will assess how antibody responses to seasonal influenza vaccination differ in individuals across multiple age groups. Baseline serum neutralizing antibodies to post-vaccination serum neutralizing antibodies against the influenza A (H1N1 and H3N2) and influenza B viral strains that are included in the quadrivalent influenza vaccine will be compared. The investigators will compare neutralizing antibody titers between groups of individuals with different birth years. Neutralizing antibody titers against the vaccine strains will be quantified by focus reduction neutralization test (FRNT) and data will be expressed as FRNT titer.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Provision of signed and dated informed consent form
- Stated willingness to comply with all study procedures and availability for all study visits
- Aged 18 years and older
- In good health based on self-reported medical conditions via an online survey
Exclusion criteria
- Known allergic reactions to components of the study vaccine
- Known latex allergy
- History of severe reactions following previous immunization with licensed or unlicensed influenza virus vaccines
- History of GBS within 6 weeks of receipt of a previous influenza vaccine
- Immunosuppression as a result of an underlying illness or treatment with immunosuppressive or cytotoxic drugs, or use of anticancer chemotherapy or radiation therapy within the preceding 36 months
- Treatment with immunoglobulin or another blood product within the 3 months prior to enrollment in this study
- Active neoplastic disease (excluding non-melanoma skin cancer or prostate cancer that is stable in the absence of therapy) or a history of any hematological malignancy ("active" is defined as having received treatment within the past 5 years)
- Long-term (greater than 2 weeks) usage of oral or parenteral steroids, or high-dose inhaled steroids
- Administration of an influenza vaccine within 2 months prior to enrollment
- Known acute or chronic medical condition that, in the opinion of the investigator or appropriate sub-investigator, would render vaccination unsafe or would interfere with the evaluation of responses
- Participation in a study that involves an experimental agent or having received an experimental agent (other than a COVID-19 vaccine) within 1 month prior to enrollment or expecting to receive another experimental agent during the study period
- Intends to donate blood during the study period
- Any condition that would, in the opinion of the site investigator, place the subject at an unacceptable risk of injury or render the subject unable to meet the requirements of the protocol
- Known human immunodeficiency virus, hepatitis B, or hepatitis C infection
- Any condition that the principal investigator believes may interfere with successful completion of the study
Where
- Philadelphia, Pennsylvania
Collaborators
National Institute of Allergy and Infectious Diseases (NIAID), Stanford University, The Scripps Research Institute
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Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Feb 9, 2026 · Source of record for eligibility and locations