InfluenzaPhase 4NCT06518577
Immunogenicity of Influenza Vaccinations
A Phase 4 study testing Flucelvax® (ccIIV3) and Flublok® (RIV3) in people with Influenza, run by Duke University at 7 sites in United States.
Trial summary
This study is a randomized immunogenicity study in an enrolled cohort with active surveillance for influenza-like illness (ILI). During this study, participants will be randomly assigned to receive an approved cell culture-based influenza vaccine (Flucelvax®) versus a licensed comparator influenza vaccine (Flublok®). Read more about this study
- Who is it for?
- Ages 18 to 64 yearsHealthy volunteers can take part
- Conditions the study is for
- Influenza
- What is being tested?
- Flucelvax® (ccIIV3) and Flublok® (RIV3)
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 606 participants
- Where
- 7 sitesUnited States
- Study dates
- 9 Sep 2024to 4 Jun 2025
- Phase
- Phase 4
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 64 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Adults aged 18-64 years that have not received the current season's influenza vaccine
- English literate
- Email or text message capability for weekly follow-up
- Intention of receiving influenza vaccine based on ACIP-CDC guidelines
- Willing to provide written/electronic informed consent
- Intention of being available for entire study period and able to complete all relevant study procedures, including follow-up phone calls and clinic visits
Who cannot join
- Receipt of the current season's influenza vaccine (receipt after July 1, 2024)
- History of severe allergic reaction after a previous dose of any influenza vaccine or to an influenza vaccine component
- Receipt of any licensed or investigational live vaccine within 6 weeks or non-live vaccine within 2 weeks prior to enrollment in this study or planning receipt of any vaccines between visits 1 and 2 of the study (approximately within 4 weeks after the receipt of study-administered vaccine)
- History of Guillain-Barré syndrome
- Currently pregnant, planning to become pregnant within the first three months of the study per participant self-report
- Bleeding diathesis or condition associated with prolonged bleeding that would, in the opinion of the investigator, contraindicate intramuscular injection.
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- Any condition which, in the opinion of the investigators, may pose a health risk to the participant or interfere with the evaluation of the study objectives
- Temporary Delay Criteria (Visit 1)
- 1. History of febrile illness (> 100.0°F or 37.8°C) within the past 72 hours prior to vaccine administration
Trial locations and contacts
7 sites in 1 country.
7 sites in 1 country
United States7 sites
Centers for Disease Control and Prevention
Atlanta, Georgia, 30333
University Hospitals Cleveland Medical Center
Cleveland, Ohio, 44106
VA Northeast Ohio Healthcare System (VANEOHS)
Cleveland, Ohio, 44106
Valleywise Health Comprehensive Health Center
Phoenix, Arizona, 85008
Department of Family Medicine, University of Pittsburgh School of Medicine
Pittsburgh, Pennsylvania, 15260
Washington University IDCRU
St Louis, Missouri, 63110
ASU Biodesign Institute
Tempe, Arizona, 85281
About this study
Official title: Measuring Immunity Against Circulating Influenza Viruses: Randomized Immunogenicity Study Among US Adults Aged 18-64 Years Comparing Two Approved Influenza Vaccines
This study is a randomized immunogenicity study in an enrolled cohort with active surveillance for influenza-like illness (ILI). During this study, participants will be randomly assigned to receive an approved cell culture-based influenza vaccine (Flucelvax®) versus a licensed comparator influenza vaccine (Flublok®). Blood samples from participants will be collected for measurement of biomarkers of immune response at baseline (visit 1; day 1), post-vaccination (visit 2; day 29), and post-season (visit 3; day 181). Participants will be asked if they wish to also provide saliva specimens at baseline (visit 1; day 1), post-vaccination (visit 2; day 29), and post-season (visit 3; day 181). Serum and peripheral blood mononuclear cells (PBMC) and plasma samples will be isolated from whole blood and tested for biomarkers of vaccine immunogenicity, and duration of antibody responses.
Participants will receive electronic surveys via email or text message weekly asking about changes in health status and new ILI symptoms; those reporting illness may be asked to provide a respiratory swab for laboratory testing for influenza and other respiratory viruses and up to 2 additional blood draws (acute [<10 days after symptom onset] and convalescent [28 days after acute visit if lab-confirmed positive for influenza]).
- Conditions
- Influenza
- Being tested
- Flucelvax® (ccIIV3), Flublok® (RIV3)
- Keywords
- Influenza, Immunogenicity
- Medical subject headings
- Influenza, Human
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Flucelvax® (ccIIV3)Biological
Participants will receive Flucelvax® (ccIIV3)
Flublok® (RIV3)Biological
Participants will receive Flublok® (RIV3)
| Study group | Role | What they receive |
|---|---|---|
| Flucelvax® (ccIIV3) | Experimental | Participants will receive Flucelvax® (ccIIV3) at Visit 1. Receives: Biological: Flucelvax® (ccIIV3) |
| Flublok® (RIV3) | Experimental | Participants will receive Flublok® (RIV3) at Visit 1. Receives: Biological: Flublok® (RIV3) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Percent of Participants With a Seroprotective HAI Titer (≥1:40)
The percent of participants with a seroprotective antibody titer (≥1:40) for each influenza vaccine antigen was determined. Cell-grown A(H1N1)pdm09 and B/Victoria were measured by hemagglutination inhibition (HAI), while A(H3N2) titers were measured by microneutralization.
Measured: Visit 2 (Days 28-42, Post-vaccination)
The Geometric Mean Titer (GMT) of HAI Antibody
The geometric mean antibody titer (GMT) for each influenza vaccine antigen in the 2024-2025 influenza season. GMTs were calculated as the anti-log of the mean of log-transformed titers. Cell-grown A(H1N1)pdm09 and B/Victoria were assessed by hemagglutination inhibition (HAI), whereas A(H3N2) was assessed by microneutralization.
Measured: Up to Visit 2 (Days 28-42, Post-vaccination)
Percent of Participants Demonstrating Seroconversion From Baseline
The percent of participants in each vaccination group demonstrating seroconversion from Baseline at Day 29 (defined as a titer ≥1:40 at Day 29 if the baseline titer is <1:10, or a ≥4-fold rise in titer at Day 29 if the baseline titer is ≥1:10) for each vaccine antigen. Viruses tested were cell-grown A(H1N1)pdm09 and B/Victoria using hemagglutination inhibition (HAI), and A(H3N2) using microneutralization.
Measured: Day 29 post-vaccination assessment (Visit 2; scheduled for Day 29 with an allowable window of Days 28-42 post-vaccination)
Geometric Mean Fold Rise (GMFR) in HAI Titer From Baseline
The geometric mean fold rise (GMFR) in antibody titers from Baseline to Day 29 for each influenza vaccine antigen. Cell-grown A(H1N1)pdm09 and B/Victoria were assessed using hemagglutination inhibition (HAI), whereas A(H3N2) was assessed using microneutralization.
Measured: Day 29 post-vaccination assessment (Visit 2; scheduled for Day 29 with an allowable window of Days 28-42 post-vaccination)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted24 Jul 2024
- Study start9 Sep 2024
- Primary completion9 Dec 2024
- Study completion4 Jun 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for InfluenzaStudies of the same condition, open and under way.
- More trials run by Duke UniversityThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 4
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 606 participants (actual)
Sponsor and investigators
- Lead sponsor
- Duke University
- Sponsor type
- University, hospital or other
- Collaborators
- Centers for Disease Control and Prevention, Arizona State University, University Hospitals Cleveland Medical Center, University of Pittsburgh, Washington University School of Medicine, VA Medical Center-Cleveland
- Responsible party
- Sponsor
- Investigators
- Emmanuel B Walter, MD, MPH, Principal investigator, Duke University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06518577
- Sponsor's protocol ID
- Pro00115120
- Status last verified
- Jun 2026
- First submitted
- 18 Jul 2024
- Last updated
- 28 Jul 2026
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Sumner KM, Noble EK, Grant LB, Meeker JR, Murugan V, Nordstrom L, House SL, Presti RM, Walter EB, Williams OL, Saade EA, Canaday DH, Williams KV, Zimmerman RK, Gross FL, Valencia S, Gurbaxani B, Lewis NM, Li ZN, Mishin V, Gubareva L, Zhou B, Levine MZ, Flannery B, Ellington S. Comparative immunogenicity and relative vaccine efficacy of recombinant and cell culture-based influenza vaccines: Results from a randomized trial of adults in the United States, 2024-2025. medRxiv [Preprint]. 2026 Oct 2:2026.10.01.26364413. doi: 10.64898/2026.10.01.26364413.
PubMed 42856744
Study at a glance
From the registry record, last updated by the sponsor on 28 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Measuring Immunity Against Circulating Influenza Viruses: Randomized Immunogenicity Study Among US Adults Aged 18-64 Years Comparing Two Approved Influenza Vaccines
- ClinicalTrials.gov ID
- NCT06518577
- Acronym / sponsor ID
- Pro00115120
- Conditions
- Influenza
- Keywords
- Influenza, Immunogenicity
- Phase
- Phase 4
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 606 participants (actual)
- Lead sponsor
- Duke UniversityUniversity, hospital or other
- Collaborators
- Centers for Disease Control and Prevention, Arizona State University, University Hospitals Cleveland Medical Center, University of Pittsburgh, Washington University School of Medicine, VA Medical Center-Cleveland
- Study start
- 9 Sep 2024 (actual)
- Primary completion
- 9 Dec 2024 (actual)
- Study completion
- 4 Jun 2025 (actual)
- First posted
- 24 Jul 2024 (actual)
- Results
- Posted 28 Jul 2026
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study is a randomized immunogenicity study in an enrolled cohort with active surveillance for influenza-like illness (ILI). During this study, participants will be randomly assigned to receive an approved cell culture-based influenza vaccine (Flucelvax®) versus a licensed comparator influenza vaccine (Flublok®). Blood samples from participants will be collected for measurement of biomarkers of immune response at baseline (visit 1; day 1), post-vaccination (visit 2; day 29), and post-season (visit 3; day 181). Participants will be asked if they wish to also provide saliva specimens at baseline (visit 1; day 1), post-vaccination (visit 2; day 29), and post-season (visit 3; day 181). Serum and peripheral blood mononuclear cells (PBMC) and plasma samples will be isolated from whole blood and tested for biomarkers of vaccine immunogenicity, and duration of antibody responses.
Participants will receive electronic surveys via email or text message weekly asking about changes in health status and new ILI symptoms; those reporting illness may be asked to provide a respiratory swab for laboratory testing for influenza and other respiratory viruses and up to 2 additional blood draws (acute [<10 days after symptom onset] and convalescent [28 days after acute visit if lab-confirmed positive for influenza]).
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Flucelvax® (ccIIV3) | Experimental | Biological: Flucelvax® (ccIIV3)Participants will receive Flucelvax® (ccIIV3) at Visit 1. |
| Flublok® (RIV3) | Experimental | Biological: Flublok® (RIV3)Participants will receive Flublok® (RIV3) at Visit 1. |
Who may qualify
- Ages
- 18 to 64 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (6 listed)
- Adults aged 18-64 years that have not received the current season's influenza vaccine
- English literate
- Email or text message capability for weekly follow-up
- Intention of receiving influenza vaccine based on ACIP-CDC guidelines
- Willing to provide written/electronic informed consent
Key exclusion criteria (9 listed)
- Receipt of the current season's influenza vaccine (receipt after July 1, 2024)
- History of severe allergic reaction after a previous dose of any influenza vaccine or to an influenza vaccine component
- Receipt of any licensed or investigational live vaccine within 6 weeks or non-live vaccine within 2 weeks prior to enrollment in this study or planning receipt of any vaccines between visits 1 and 2 of the study (approximately within 4 weeks after the receipt of study-administered vaccine)
- History of Guillain-Barré syndrome
- Currently pregnant, planning to become pregnant within the first three months of the study per participant self-report
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Flucelvax® (ccIIV3)Participants will receive Flucelvax® (ccIIV3) | Biological | Flucelvax® (ccIIV3) |
| Flublok® (RIV3)Participants will receive Flublok® (RIV3) | Biological | Flublok® (RIV3) |
Primary outcome
Percent of Participants With a Seroprotective HAI Titer (≥1:40)
Time frame: Visit 2 (Days 28-42, Post-vaccination)
The percent of participants with a seroprotective antibody titer (≥1:40) for each influenza vaccine antigen was determined. Cell-grown A(H1N1)pdm09 and B/Victoria were measured by hemagglutination inhibition (HAI), while A(H3N2) titers were measured by microneutralization.
The Geometric Mean Titer (GMT) of HAI Antibody
Time frame: Up to Visit 2 (Days 28-42, Post-vaccination)
The geometric mean antibody titer (GMT) for each influenza vaccine antigen in the 2024-2025 influenza season. GMTs were calculated as the anti-log of the mean of log-transformed titers. Cell-grown A(H1N1)pdm09 and B/Victoria were assessed by hemagglutination inhibition (HAI), whereas A(H3N2) was assessed by microneutralization.
Percent of Participants Demonstrating Seroconversion From Baseline
Time frame: Day 29 post-vaccination assessment (Visit 2; scheduled for Day 29 with an allowable window of Days 28-42 post-vaccination)
The percent of participants in each vaccination group demonstrating seroconversion from Baseline at Day 29 (defined as a titer ≥1:40 at Day 29 if the baseline titer is <1:10, or a ≥4-fold rise in titer at Day 29 if the baseline titer is ≥1:10) for each vaccine antigen. Viruses tested were cell-grown A(H1N1)pdm09 and B/Victoria using hemagglutination inhibition (HAI), and A(H3N2) using microneutralization.
Geometric Mean Fold Rise (GMFR) in HAI Titer From Baseline
Time frame: Day 29 post-vaccination assessment (Visit 2; scheduled for Day 29 with an allowable window of Days 28-42 post-vaccination)
The geometric mean fold rise (GMFR) in antibody titers from Baseline to Day 29 for each influenza vaccine antigen. Cell-grown A(H1N1)pdm09 and B/Victoria were assessed using hemagglutination inhibition (HAI), whereas A(H3N2) was assessed using microneutralization.
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 28 Jul 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Derived from this study: PubMed 42856744Sumner KM, Noble EK, Grant LB, Meeker JR, Murugan V, Nordstrom L, House SL, Presti RM, Walter EB, Williams OL, Saade EA, Canaday DH, Williams KV, Zimmerman RK, Gross FL, Valencia S, Gurbaxani B, Lewis NM, Li ZN, Mishin V, Gubareva L, Zhou B, Levine MZ, Flannery B, Ellington S. Comparative immunogenicity and relative vaccine efficacy of recombinant and cell culture-based influenza vaccines: Results from a randomized trial of adults in the United States, 2024-2025. medRxiv [Preprint]. 2026 Oct 2:2026.10.01.26364413. doi: 10.64898/2026.10.01.26364413.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Emmanuel B Walter, MD, MPH principal investigator
Duke University
7 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 4 study testing Flucelvax® (ccIIV3) and Flublok® (RIV3) in people with Influenza, run by Duke University at 7 sites in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 6 inclusion and 9 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 28 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 7 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
Yes. Results are posted in the registry (first posted 28 Jul 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Percent of Participants With a Seroprotective HAI Titer (≥1:40) (time frame: Visit 2 (Days 28-42, Post-vaccination)). The study lists 4 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT06518577, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 28 Jul 2026.