Recruiting
Phase 4

Influenza Vaccines

Sponsor:

University of Missouri-Columbia

Code:

NCT07910266

Conditions

Immunology

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Accepted

Interventions

Egg-Based Inactivated Influenza Vaccine

Cell-Based Inactivated Influenza Vaccine

Study Details

Brief summary:

The goal of this clinical trial is to learn how different types of influenza (flu) vaccines affect the body's immune response over time. Researchers want to understand whether receiving egg-based flu vaccines, cell-based flu vaccines, or a combination of both influences how the immune system responds to future flu vaccinations.

The main questions this study aims to answer are:

1. Does a person's previous flu vaccine type affect their immune response to a later flu vaccine?
2. Do repeated vaccinations with the same vaccine platform or switching between vaccine platforms produce different antibody responses?
3. How do different vaccination histories affect flu-specific immune cells and protection against different influenza strains?

Participants will be randomly assigned to receive one of four vaccine combinations:

  • Egg-based vaccine followed by egg-based vaccine
  • Egg-based vaccine followed by cell-based vaccine
  • Cell-based vaccine followed by cell-based vaccine
  • Cell-based vaccine followed by egg-based vaccine Researchers will compare immune responses among these groups.

Participants will:

  • Complete a baseline survey about demographics, vaccination history, medical history, and household information.
  • Receive a first seasonal influenza vaccination (egg-based or cell-based, depending on random assignment).
  • Provide blood samples before vaccination and several times afterward to measure immune responses.
  • Receive a second study influenza vaccination approximately 3 months after the first vaccination.
  • Continue providing blood samples after the second vaccination.
  • Complete brief follow-up surveys about health changes, additional vaccinations, and influenza-like illness during the study.

Blood samples will be collected up to eight times during each study year:

1. Before or on the day of the first vaccination
2. About 1 week after the first vaccination
3. About 1 month after the first vaccination
4. About 3 months after the first vaccination (the second vaccination will be given at this visit)
5. About 1 week after the second vaccination
6. About 1 month after the second vaccination
7. About 3 months after the second vaccination
8. About 6 months after the second vaccination

Participants may be observed for approximately 15 minutes after vaccination, consistent with routine vaccination practices.

Prior to the second vaccination, participants will be evaluated for any reasons that might make vaccination unsafe or require postponement. Participants who are able to become pregnant will complete a urine pregnancy test before the second vaccination. Participants who are pregnant or have a positive pregnancy test will not receive the second study vaccination but may continue study follow-up activities, including blood collection and surveys.

Participation in each study year lasts up to 10 months. Participants may choose to continue participating annually for up to 7 years.

Blood samples and related study data may be stored in a secure research biorepository for future studies related to infectious diseases, immunology, vaccine responses, and other health conditions. Stored samples will be coded to protect participant privacy, and identifying information will not be shared without appropriate approvals and participant authorization

Conditions

Immunology

Study ID

NCT07910266

Start date

Oct, 2026

Status verified date

Oct, 2026

Completion date

Sep, 2027

Anticipated

Primary completion date

Feb, 2027

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Accepted

Inclusion Criteria:

  • Did NOT receive a flu shot last year
  • Planning to get flu shot this year;
  • 18 years of age or older;
  • English speaking
  • Willing to be randomized to receive either FDA-approved cell-based or egg-based flu vaccination
  • Willing to get a second flu shot about 3 months after the first one

Exclusion Criteria:

  • Received a flu shot last year
  • Less than 18 years old
  • Not willing to be directed to get a certain type of vaccination
  • Not willing to get a flu vaccination or a second vaccination during the study period
  • Does not speak English
  • History of severe allergic reaction (e.g., anaphylaxis) following a previous influenza vaccine or to a component of the study vaccine.
  • Have a history of Guillain-Barré Syndrome within 6 weeks of a previous influenza vaccination.
  • Women who are pregnant or may be pregnant will not receive the second study vaccination

Study Design

Enrollment

220 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Basic Science

Interventions and Outcome Measures

Arms

experimental: Egg-Based → Egg-Based (E-E)

E-E: Participants receive an egg-based inactivated influenza vaccine at the first vaccination and an egg-based inactivated influenza vaccine approximately 3 months later.

experimental: Egg-Based → Cell-Based (E-C)

Participants receive an egg-based inactivated influenza vaccine at the first vaccination and a cell-based inactivated influenza vaccine approximately 3 months later.

experimental: Cell-Based → Cell-Based (C-C)

Participants receive a cell-based inactivated influenza vaccine at the first vaccination and a cell-based inactivated influenza vaccine approximately 3 months later.

experimental: Cell-Based → Egg-Based (C-E)

Participants receive a cell-based inactivated influenza vaccine at the first vaccination and an egg-based inactivated influenza vaccine approximately 3 months later.

Interventions

Egg-Based Inactivated Influenza Vaccine

Participants receive a licensed egg-based inactivated influenza vaccine at one or both study vaccination visits.

Cell-Based Inactivated Influenza Vaccine

Participants receive a licensed cell-based inactivated influenza vaccine at one or both study vaccination visits.

Primary outcome measure

  • Change from Baseline in Hemagglutination Inhibition (HAI) Antibody Geometric Mean Titers at 1 Month After the Second Vaccination [ Time Frame: Before the first vaccination and 1 month after the second vaccination. ]

Central Contacts and Locations

Central contacts

Anna Zakrzewicz, PhD

573-882-3202annazakrzewicz@umsystem.edu

Jane A McElroy, PhD

573-882-4993mcelroyja@umsystem.edu

Locations

University of Missouri Systems

Recruiting

Columbia, Missouri, United States, 65212

Contacts

Anna Zakrzewicz, PhD

annazakrzewicz@health.missouri.edu

Jane A McElroy, PhD

573-882-4993mcelroyja@umsystem.edu

Principal Investigator:

Xiu-Feng Wan, PhD

More Information

Sponsor

University of Missouri-Columbia

Last update posted

Nov 2, 2026

Last verified

Oct, 2026

Keywords

  • Influenza vaccination
  • egg-based vaccine
  • cell-based vaccine

Trial information was received from ClinicalTrials.gov and was last updated on 2026-11-03. This information was provided to ClinicalTrials.gov by University of Missouri-Columbia on 2026-11-02. Recruitment status is synced daily from ClinicalTrials.gov and may not reflect the sponsor's current status. Confirm during your call.