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Completed

NCT Number: NCT06518577

Immunogenicity of Influenza Vaccinations

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]).

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Key information

Conditions

Influenza Infections Influenza, Human Orthomyxoviridae Infections RNA Virus Infections Respiratory Tract Diseases Respiratory Tract Infections Virus Diseases

Age range

18 year–64 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 4

Primary location

Valleywise Health Comprehensive Health Center, Phoenix, Arizona, United States

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Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 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

Exclusion criteria

  • 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.
  • 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)

  • History of febrile illness (> 100.0°F or 37.8°C) within the past 72 hours prior to vaccine administration

Treatment and study plan

Flucelvax® (ccIIV3)

Biological

Participants will receive Flucelvax® (ccIIV3)

Flublok® (RIV3)

Biological

Participants will receive Flublok® (RIV3)

Primary outcomes

  1. 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.

  2. 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.

  3. 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.

  4. 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.

Sponsors and collaborators

Lead sponsor

Duke University

Other

Collaborators

  • Arizona State University
  • Centers for Disease Control and Prevention
  • University Hospitals Cleveland Medical Center
  • University of Pittsburgh
  • VA Medical Center-Cleveland
  • Washington University School of Medicine

Registry information

Official study title

Measuring Immunity Against Circulating Influenza Viruses: Randomized Immunogenicity Study Among US Adults Aged 18-64 Years Comparing Two Approved Influenza Vaccines

Important dates

Study start
2024
Primary completion
2024
Study completion
2025
First posted
Jul 24, 2024
Registry last updated
Jul 28, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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