Influenza, HumanPhase 1/2NCT06436703
A Study About Modified RNA Vaccines Against Influenza in Healthy Adults
A Phase 1/2 study testing Influenza ModRNA Vaccine and Quadrivalent Influenza Vaccine (QIV) in people with Influenza, Human, run by Pfizer at 32 sites in United States.
Trial summary
The purpose of this study is to learn if modified RNA (modRNA) vaccines for the prevention of influenza are: safe; and how these vaccines produce an immune response in generally healthy adults. Immune response is the way the body protects itself against things it sees as harmful or foreign. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Influenza, Human
- What is being tested?
- Influenza ModRNA Vaccine and Quadrivalent Influenza Vaccine (QIV)
- Type of treatment
- Vaccines, Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 1,202 participants
- Where
- 32 sitesUnited States
- Study dates
- 23 May 2024to 5 Feb 2025
- Phase
- Phase 1/2
- 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 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Applies to all 3 substudies:
- participants ≥18 years of age.
- generally healthy participants.
- Substudy C ONLY:
- receipt of licensed influenza vaccination for the 2023-2024 flu season at least 6 months ago.
Who cannot join
- All 3 substudies:
- diagnosis of influenza (by clinical testing) in the last 6 months.
- immunocompromised individuals with known or suspected immunodeficiency
- receipt of any investigational or licensed influenza vaccines within 6 months.
Trial locations and contacts
32 sites in 1 country.
32 sites in 1 country
United States32 sites
Anaheim Clinical Trials, LLC
Anaheim, California, 92801
Headlands Horizons LLC
Brownsville, Texas, 78526
Charlottesville Medical Research
Charlottesville, Virginia, 22911
Clinical Research Professionals
Chesterfield, Missouri, 63005
Duke Vaccine and Trials Unit
Durham, North Carolina, 27703
Indago Research & Health Center, Inc
Hialeah, Florida, 33012
Research Centers of America ( Hollywood )
Hollywood, Florida, 33024
Research Centers of America
Hollywood, Florida, 33024
East-West Medical Research Institute
Honolulu, Hawaii, 96814
Alliance for Multispecialty Research, LLC
Kansas City, Missouri, 64114
Orange County Research Center
Lake Forest, California, 92630
SMS Clinical Research
Mesquite, Texas, 75149
Palm Springs Community Health Center
Miami Lakes, Florida, 33014
Clinical Research Consulting
Milford, Connecticut, 06460
AMR Clinical
Mobile, Alabama, 36608
Alliance for Multispecialty Research, LLC
New Orleans, Louisiana, 70119
AMR Clinical
Norfolk, Virginia, 23502
Clinical Neuroscience Solutions, Inc.
Orlando, Florida, 32801
Headlands Research Orlando
Orlando, Florida, 32819
DM Clinical Research - Philadelphia
Philadelphia, Pennsylvania, 19107
M3 Wake Research, Inc.
Raleigh, North Carolina, 27612
Rochester Clinical Research, LLC
Rochester, New York, 14609
Prism Research LLC dba Nucleus Network
Saint Paul, Minnesota, 55114
J. Lewis Research, Inc. / Foothill Family Clinic
Salt Lake City, Utah, 84109
J. Lewis Research, Inc. / Foothill Family Clinic South
Salt Lake City, Utah, 84121
Clinical Trials of Texas, LLC dba Flourish Research
San Antonio, Texas, 78229
Clinical Trials of Texas, LLC
San Antonio, Texas, 78229
Artemis Institute for Clinical Research
San Diego, California, 92103
Headlands Research - Scottsdale
Scottsdale, Arizona, 85260
Qps-Mra, Llc
South Miami, Florida, 33143
Dynamed Clinical Research, LP d/b/a DM Clinical Research
Tomball, Texas, 77375
Diablo Clinical Research, Inc.
Walnut Creek, California, 94598
About this study
Official title: A STUDY TO EVALUATE THE SAFETY, TOLERABILITY, AND IMMUNOGENICITY OF MODIFIED RNA VACCINES AGAINST INFLUENZA IN HEALTHY ADULTS
The purpose of this study is to learn if modified RNA (modRNA) vaccines for the prevention of influenza are:
- safe; and
- how these vaccines produce an immune response in generally healthy adults. Immune response is the way the body protects itself against things it sees as harmful or foreign.
Read more
RNA (also called ribonucleic acid) is one of two types of nucleic acid made by cells. RNA contains information that has been copied from DNA (the other type of nucleic acid). Cells make several different forms of RNA, and each form has a specific job in the cell. Many forms of RNA have functions related to making proteins. RNA is also the genetic material of some viruses instead of DNA. RNA can be made in the laboratory and used in research studies. Also called ribonucleic acid.
Influenza is term used for flu illness. It is an infection caused by a virus that affects your mouth, nose, and throat.
The study is seeking for participants who:
- are at least 18 years of age
- have not received an influenza vaccine within the last 6 months
- are generally healthy
This study will be divided into three sub-studies: Substudy A (SSA), Substudy B (SSB), and Substudy C (SSC).
All participants, regardless of sub-study, will receive 1 dose of either of the following vaccines as an injection into their arm:
- 1 of the modRNA influenza vaccines that is being studied; or
- an approved influenza vaccine approved for use in their respective age group.
Participants will be involved in this study for about 6 months. During this time, participants will have at least 3 clinic visits.
- Conditions
- Influenza, Human
- Being tested
- Influenza ModRNA Vaccine, Quadrivalent Influenza Vaccine (QIV)
- Medical subject headings
- Influenza, Human
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Influenza ModRNA VaccineBiological
Intramuscular injection
Quadrivalent Influenza Vaccine (QIV)Biological
Intramuscular injection
| Study group | Role | What they receive |
|---|---|---|
| SSA: Influenza ModRNA Vaccine 2A | Experimental | - Single Dose on Day 1 Receives: Biological: Influenza ModRNA Vaccine |
| SSA: Influenza ModRNA Vaccine 3A | Experimental | - Single Dose on Day 1 Receives: Biological: Influenza ModRNA Vaccine |
| SSA: Influenza ModRNA Vaccine 4A | Experimental | - Single Dose on Day 1 Receives: Biological: Influenza ModRNA Vaccine |
| SSA: Influenza ModRNA Vaccine 5A | Experimental | - Single dose on Day 1 Receives: Biological: Influenza ModRNA Vaccine |
| SSA: QIV1 | Active comparator | - Single dose on Day 1 Receives: Biological: Quadrivalent Influenza Vaccine (QIV) |
| SSB: Influenza ModRNA Vaccine 3B | Experimental | - Single Dose on Day 1 Receives: Biological: Influenza ModRNA Vaccine |
| SSB: Influenza ModRNA Vaccine 4B | Experimental | - Single Dose on Day 1 Receives: Biological: Influenza ModRNA Vaccine |
| SSB: Influenza ModRNA Vaccine 5B | Experimental | - Single dose on Day 1 Receives: Biological: Influenza ModRNA Vaccine |
| SSB: QIV2 | Active comparator | - Single Dose on Day 1 Receives: Biological: Quadrivalent Influenza Vaccine (QIV) |
| SSB: QIV3 | Active comparator | - Single Dose on Day 1 Receives: Biological: Quadrivalent Influenza Vaccine (QIV) |
| SSC: Influenza ModRNA Vaccine 3C | Experimental | - Single Dose on Day 1 Receives: Biological: Influenza ModRNA Vaccine |
| SSC: Influenza ModRNA Vaccine 4C | Experimental | - Single Dose on Day 1 Receives: Biological: Influenza ModRNA Vaccine |
| SSC: Influenza ModRNA Vaccine 5C | Experimental | - Single Dose on Day 1 Receives: Biological: Influenza ModRNA Vaccine |
| SSC: Influenza ModRNA Vaccine 6C | Experimental | - Single Dose on Day 1 Receives: Biological: Influenza ModRNA Vaccine |
| SSC: Influenza ModRNA Vaccine 7C | Experimental | - Single Dose on Day 1 Receives: Biological: Influenza ModRNA Vaccine |
| SSC: Influenza ModRNA Vaccine 8C | Experimental | - Single Dose on Day 1 Receives: Biological: Influenza ModRNA Vaccine |
| SSC: Influenza ModRNA Vaccine 9C | Experimental | - Single dose on Day 1 Receives: Biological: Influenza ModRNA Vaccine |
| SSC: QIV2 | Active comparator | - Single Dose on Day 1 Receives: Biological: Quadrivalent Influenza Vaccine (QIV) |
| SSC: QIV3 | Active comparator | - Single Dose on Day 1 Receives: Biological: Quadrivalent Influenza Vaccine (QIV) |
What is being measured
The primary outcome is the main question the study is designed to answer.
SSA: Percentage of Participants With Local Reactions for up to 7 Days Following Vaccination
Local reactions included pain at the injection site, redness and swelling and were recorded by participants in the electronic dairy (e-diary) or by investigators in case report form (CRF) after vaccination. All local reactions were graded based on center for biologics evaluation and research (CBER) toxicity guidelines as Grade 1 (Mild), Grade 2 (Moderate), Grade 3 (Severe) and Grade 4 (potentially life-threatening). In this outcome measure, data is reported as percentage of participants with any local reaction of any grade.
Measured: From Day 1 through Day 7 after study vaccination [Vaccination on Day 1]
SSB: Percentage of Participants With Local Reactions for up to 7 Days Following Vaccination
Local reactions included pain at the injection site, redness and swelling and were recorded by participants in the e-diary or by investigators in CRF after vaccination. All local reactions were graded based on CBER toxicity guidelines as Grade 1 (Mild), Grade 2 (Moderate), Grade 3 (Severe) and Grade 4 (potentially life-threatening). In this outcome measure, data is reported as percentage of participants with any local reaction of any grade.
Measured: From Day 1 through Day 7 after study vaccination [Vaccination on Day 1]
SSC: Percentage of Participants With Local Reactions for up to 7 Days Following Vaccination
Local reactions included pain at the injection site, redness and swelling and were recorded by participants in the e-diary or by investigators in CRF after vaccination. All local reactions were graded based on CBER toxicity guidelines as Grade 1 (Mild), Grade 2 (Moderate), Grade 3 (Severe) and Grade 4 (potentially life-threatening). In this outcome measure, data is reported as percentage of participants with any local reaction of any grade.
Measured: From Day 1 through Day 7 after study vaccination [Vaccination on Day 1]
SSA: Percentage of Participants With Systemic Events for up to 7 Days Following Vaccination
Systemic events (fever, vomiting, diarrhea, headache, fatigue, chills, new or worsened muscle pain and joint pain) were recorded by participants in the e-diary or by investigators in CRF after vaccination. All systemic events were graded based on CBER toxicity guidelines as Grade 1 (Mild), Grade 2 (Moderate), Grade 3 (Severe) and Grade 4 (potentially life-threatening). In this outcome measure, data is reported as percentage of participants with any systemic events of any grade.
Measured: From Day 1 through Day 7 after study vaccination [Vaccination on Day 1]
SSB: Percentage of Participants With Systemic Events for up to 7 Days Following Vaccination
Systemic events (fever, vomiting, diarrhea, headache, fatigue, chills, new or worsened muscle pain and joint pain) were recorded by participants in the e-diary or by investigators in CRF after vaccination. All systemic events were graded based on CBER toxicity guidelines as Grade 1 (Mild), Grade 2 (Moderate), Grade 3 (Severe) and Grade 4 (potentially life-threatening). In this outcome measure, data is reported as percentage of participants with any systemic events of any grade.
Measured: From Day 1 through Day 7 after study vaccination [Vaccination on Day 1]
SSC: Percentage of Participants With Systemic Events for up to 7 Days Following Vaccination
Systemic events (fever, vomiting, diarrhea, headache, fatigue, chills, new or worsened muscle pain and joint pain) were recorded by participants in the e-diary or by investigators in CRF after vaccination. All systemic events were graded based on CBER toxicity guidelines as Grade 1 (Mild), Grade 2 (Moderate), Grade 3 (Severe) and Grade 4 (potentially life-threatening). In this outcome measure, data is reported as percentage of participants with any systemic events of any grade.
Measured: From Day 1 through Day 7 after study vaccination [Vaccination on Day 1]
SSA: Percentage of Participants With Adverse Events (AEs) From Vaccination Through 4 Weeks After Vaccination
An AE was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. Only AEs collected by non-systematic assessment (excluding local reactions and systematic events) were included in this outcome measure.
Measured: From study vaccination on Day 1 through 4 weeks after study vaccination
SSB: Percentage of Participants With AEs From Vaccination Through 4 Weeks After Vaccination
An AE was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. Only AEs collected by non-systematic assessment (excluding local reactions and systematic events) were included in this outcome measure.
Measured: From study vaccination on Day 1 through 4 weeks after study vaccination
SSC: Percentage of Participants With AEs From Vaccination Through 4 Weeks After Vaccination
An AE was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. Only AEs collected by non-systematic assessment (excluding local reactions and systematic events) were included in this outcome measure.
Measured: From study vaccination on Day 1 through 4 weeks after study vaccination
SSA: Percentage of Participants With SAEs From Vaccination Through 6 Months After Vaccination
An SAE was defined as any untoward medical occurrence that, at any dose, met one or more of the following criteria: resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, was a congenital anomaly/birth defect, any other pre-specified criteria in protocol of the study or other important medical event judged by the investigator.
Measured: From study vaccination on Day 1 through 6 months after study vaccination
SSB: Percentage of Participants With SAEs From Vaccination Through 6 Months After Vaccination
An SAE was defined as any untoward medical occurrence that, at any dose, met one or more of the following criteria: resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, was a congenital anomaly/birth defect, any other pre-specified criteria in protocol of the study or other important medical event judged by the investigator.
Measured: From study vaccination on Day 1 through 6 months after study vaccination
SSC: Percentage of Participants With SAEs From Vaccination Through 6 Months After Vaccination
An SAE was defined as any untoward medical occurrence that, at any dose, met one or more of the following criteria: resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, was a congenital anomaly/birth defect, any other pre-specified criteria in protocol of the study or other important medical event judged by the investigator.
Measured: From study vaccination on Day 1 through 6 months after study vaccination
SSA: Percentage of Participants With Medically Attended Adverse Events (MAEs) From Vaccination Through 6 Months After Vaccination
An MAE was defined as a non-serious AE that resulted in an evaluation at a medical facility.
Measured: From study vaccination on Day 1 through 6 months after study vaccination
SSB: Percentage of Participants With MAEs From Vaccination Through 6 Months After Vaccination
An MAE was defined as a non-serious AE that resulted in an evaluation at a medical facility.
Measured: From study vaccination on Day 1 through 6 months after study vaccination
SSC: Percentage of Participants With MAEs From Vaccination Through 6 Months After Vaccination
An MAE was defined as a non-serious AE that resulted in an evaluation at a medical facility.
Measured: From study vaccination on Day 1 through 6 months after study vaccination
SSA: Percentage of Participants With Newly Diagnosed Chronic Medical Conditions (NDCMCs) From Vaccination Through 6 Months After Vaccination
An NDCMC was defined as a disease or medical condition, not previously identified, that was expected to be persistent or otherwise long-lasting in its effects (e.g., asthma).
Measured: From study vaccination on Day 1 through 6 months after study vaccination
SSB: Percentage of Participants With NDCMCs From Vaccination Through 6 Months After Vaccination
An NDCMC was defined as a disease or medical condition, not previously identified, that was expected to be persistent or otherwise long-lasting in its effects (e.g., asthma).
Measured: From study vaccination on Day 1 through 6 months after study vaccination
SSC: Percentage of Participants With NDCMCs From Vaccination Through 6 Months After Vaccination
An NDCMC was defined as a disease or medical condition, not previously identified, that was expected to be persistent or otherwise long-lasting in its effects (e.g., asthma).
Measured: From study vaccination on Day 1 through 6 months after study vaccination
Secondary outcomes (8)
SSA: Geometric Mean Titers (GMTs) of Strain-Specific Hemagglutination Inhibition Assay (HAI) Titers at Baseline and 4 Weeks After Vaccination
GMTs and the corresponding 2-sided 95% confidence intervals (CIs) were calculated by exponentiating the mean logarithm of the titers and the corresponding CIs (based on the Student t distribution).
Measured: Baseline (before study vaccination on Day 1), 4 weeks after study vaccination
SSA: Geometric Mean Fold Rise (GMFR) of Strain-Specific HAI Titers From Before Vaccination to 4 Weeks After Vaccination
GMFR was defined as the geometric mean of the fold rise in the assay results from before vaccination to a specified time point after vaccination.
Measured: From before study vaccination on Day 1 up to 4 weeks after study vaccination
SSA: Percentage of Participants Achieving HAI Seroconversion for Each Strain at 4 Weeks After Vaccination
Seroconversion was defined as an HAI titer <1:10 prior to vaccination and >=1:40 at the time point of interest, or an HAI titer of >=1:10 prior to vaccination with at least a 4-fold rise at the time point of interest.
Measured: 4 weeks after study vaccination
SSA: Percentage of Participants With HAI Titers >=1:40 For Each Strain at Baseline and 4 Weeks After Vaccination
This measure is for percentage of participants achieving HAI titers >=1:40 for each strain.
Measured: Baseline (before study vaccination on Day 1), 4 weeks after study vaccination
SSB: GMTs of Strain-Specific HAI Titers at Baseline and 4 Weeks After Vaccination
Measured: Baseline (before study vaccination on Day 1), 4 weeks after study vaccination
SSB: GMFRs of Strain-Specific HAI Titers From Before Vaccination to 4 Weeks After Vaccination
Measured: From before study vaccination on Day 1 up to 4 weeks after study vaccination
SSB: Percentage of Participants Achieving HAI Seroconversion for Each Strain at 4 Weeks After Vaccination
Measured: 4 weeks after study vaccination
SSB: Percentage of Participants With HAI Titers >=1:40 For Each Strain at Baseline and 4 Weeks After Vaccination
This measure is for percentage of participants achieving HAI titers >=1:40 for each strain.
Measured: Baseline (before study vaccination on Day 1), 4 weeks after study vaccination
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted31 May 2024
- Study start23 May 2024
- Primary completion5 Feb 2025
- Study completion5 Feb 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.
- Other trials for Influenza, HumanStudies of the same condition, open and under way.
- More trials run by PfizerThe 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 1/2
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 1,202 participants (actual)
Sponsor and investigators
- Lead sponsor
- Pfizer
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Pfizer CT.gov Call Center, Study director, Pfizer
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06436703
- Sponsor's protocol ID
- C4781013
- Other IDs
- NCT06436703
- Status last verified
- Jun 2026
- First submitted
- 24 May 2024
- Last updated
- 12 Jun 2026
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.
Study at a glance
From the registry record, last updated by the sponsor on 12 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A STUDY TO EVALUATE THE SAFETY, TOLERABILITY, AND IMMUNOGENICITY OF MODIFIED RNA VACCINES AGAINST INFLUENZA IN HEALTHY ADULTS
- ClinicalTrials.gov ID
- NCT06436703
- Acronym / sponsor ID
- C4781013
- Conditions
- Influenza, Human
- Phase
- Phase 1/2
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 1,202 participants (actual)
- Lead sponsor
- PfizerIndustry (pharma, biotech, devices)
- Study start
- 23 May 2024 (actual)
- Primary completion
- 5 Feb 2025 (actual)
- Study completion
- 5 Feb 2025 (actual)
- First posted
- 31 May 2024 (actual)
- Results
- Posted 12 Jun 2026
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of this study is to learn if modified RNA (modRNA) vaccines for the prevention of influenza are:
- safe; and
- how these vaccines produce an immune response in generally healthy adults. Immune response is the way the body protects itself against things it sees as harmful or foreign.
RNA (also called ribonucleic acid) is one of two types of nucleic acid made by cells. RNA contains information that has been copied from DNA (the other type of nucleic acid). Cells make several different forms of RNA, and each form has a specific job in the cell. Many forms of RNA have functions related to making proteins. RNA is also the genetic material of some viruses instead of DNA. RNA can be made in the laboratory and used in research studies. Also called ribonucleic acid.
Influenza is term used for flu illness. It is an infection caused by a virus that affects your mouth, nose, and throat.
The study is seeking for participants who:
- are at least 18 years of age
- have not received an influenza vaccine within the last 6 months
- are generally healthy
This study will be divided into three sub-studies: Substudy A (SSA), Substudy B (SSB), and Substudy C (SSC).
All participants, regardless of sub-study, will receive 1 dose of either of the following vaccines as an injection into their arm:
- 1 of the modRNA influenza vaccines that is being studied; or
- an approved influenza vaccine approved for use in their respective age group.
Participants will be involved in this study for about 6 months. During this time, participants will have at least 3 clinic visits.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 19
| Arm | Type | Receives |
|---|---|---|
| SSA: Influenza ModRNA Vaccine 2A | Experimental | Biological: Influenza ModRNA Vaccine- Single Dose on Day 1 |
| SSA: Influenza ModRNA Vaccine 3A | Experimental | Biological: Influenza ModRNA Vaccine- Single Dose on Day 1 |
| SSA: Influenza ModRNA Vaccine 4A | Experimental | Biological: Influenza ModRNA Vaccine- Single Dose on Day 1 |
| SSA: Influenza ModRNA Vaccine 5A | Experimental | Biological: Influenza ModRNA Vaccine- Single dose on Day 1 |
| SSA: QIV1 | Active comparator | Biological: Quadrivalent Influenza Vaccine (QIV)- Single dose on Day 1 |
| SSB: Influenza ModRNA Vaccine 3B | Experimental | Biological: Influenza ModRNA Vaccine- Single Dose on Day 1 |
| SSB: Influenza ModRNA Vaccine 4B | Experimental | Biological: Influenza ModRNA Vaccine- Single Dose on Day 1 |
| SSB: Influenza ModRNA Vaccine 5B | Experimental | Biological: Influenza ModRNA Vaccine- Single dose on Day 1 |
| SSB: QIV2 | Active comparator | Biological: Quadrivalent Influenza Vaccine (QIV)- Single Dose on Day 1 |
| SSB: QIV3 | Active comparator | Biological: Quadrivalent Influenza Vaccine (QIV)- Single Dose on Day 1 |
| SSC: Influenza ModRNA Vaccine 3C | Experimental | Biological: Influenza ModRNA Vaccine- Single Dose on Day 1 |
| SSC: Influenza ModRNA Vaccine 4C | Experimental | Biological: Influenza ModRNA Vaccine- Single Dose on Day 1 |
| SSC: Influenza ModRNA Vaccine 5C | Experimental | Biological: Influenza ModRNA Vaccine- Single Dose on Day 1 |
| SSC: Influenza ModRNA Vaccine 6C | Experimental | Biological: Influenza ModRNA Vaccine- Single Dose on Day 1 |
| SSC: Influenza ModRNA Vaccine 7C | Experimental | Biological: Influenza ModRNA Vaccine- Single Dose on Day 1 |
| SSC: Influenza ModRNA Vaccine 8C | Experimental | Biological: Influenza ModRNA Vaccine- Single Dose on Day 1 |
| SSC: Influenza ModRNA Vaccine 9C | Experimental | Biological: Influenza ModRNA Vaccine- Single dose on Day 1 |
| SSC: QIV2 | Active comparator | Biological: Quadrivalent Influenza Vaccine (QIV)- Single Dose on Day 1 |
| SSC: QIV3 | Active comparator | Biological: Quadrivalent Influenza Vaccine (QIV)- Single Dose on Day 1 |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- participants ≥18 years of age.
- generally healthy participants.
- receipt of licensed influenza vaccination for the 2023-2024 flu season at least 6 months ago.
Key exclusion criteria (4 listed)
- diagnosis of influenza (by clinical testing) in the last 6 months.
- immunocompromised individuals with known or suspected immunodeficiency
- receipt of any investigational or licensed influenza vaccines within 6 months.
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 |
|---|---|---|
| Influenza ModRNA VaccineIntramuscular injection | Biological | SSA: Influenza ModRNA Vaccine 2A, SSA: Influenza ModRNA Vaccine 3A, SSA: Influenza ModRNA Vaccine 4A, SSA: Influenza ModRNA Vaccine 5A, SSB: Influenza ModRNA Vaccine 3B, SSB: Influenza ModRNA Vaccine 4B, SSB: Influenza ModRNA Vaccine 5B, SSC: Influenza ModRNA Vaccine 3C, SSC: Influenza ModRNA Vaccine 4C, SSC: Influenza ModRNA Vaccine 5C, SSC: Influenza ModRNA Vaccine 6C, SSC: Influenza ModRNA Vaccine 7C, SSC: Influenza ModRNA Vaccine 8C, SSC: Influenza ModRNA Vaccine 9C |
| Quadrivalent Influenza Vaccine (QIV)Intramuscular injection | Biological | SSA: QIV1, SSB: QIV2, SSB: QIV3, SSC: QIV2, SSC: QIV3 |
Primary outcome
SSA: Percentage of Participants With Local Reactions for up to 7 Days Following Vaccination
Time frame: From Day 1 through Day 7 after study vaccination [Vaccination on Day 1]
Local reactions included pain at the injection site, redness and swelling and were recorded by participants in the electronic dairy (e-diary) or by investigators in case report form (CRF) after vaccination. All local reactions were graded based on center for biologics evaluation and research (CBER) toxicity guidelines as Grade 1 (Mild), Grade 2 (Moderate), Grade 3 (Severe) and Grade 4 (potentially life-threatening). In this outcome measure, data is reported as percentage of participants with any local reaction of any grade.
SSB: Percentage of Participants With Local Reactions for up to 7 Days Following Vaccination
Time frame: From Day 1 through Day 7 after study vaccination [Vaccination on Day 1]
Local reactions included pain at the injection site, redness and swelling and were recorded by participants in the e-diary or by investigators in CRF after vaccination. All local reactions were graded based on CBER toxicity guidelines as Grade 1 (Mild), Grade 2 (Moderate), Grade 3 (Severe) and Grade 4 (potentially life-threatening). In this outcome measure, data is reported as percentage of participants with any local reaction of any grade.
SSC: Percentage of Participants With Local Reactions for up to 7 Days Following Vaccination
Time frame: From Day 1 through Day 7 after study vaccination [Vaccination on Day 1]
Local reactions included pain at the injection site, redness and swelling and were recorded by participants in the e-diary or by investigators in CRF after vaccination. All local reactions were graded based on CBER toxicity guidelines as Grade 1 (Mild), Grade 2 (Moderate), Grade 3 (Severe) and Grade 4 (potentially life-threatening). In this outcome measure, data is reported as percentage of participants with any local reaction of any grade.
SSA: Percentage of Participants With Systemic Events for up to 7 Days Following Vaccination
Time frame: From Day 1 through Day 7 after study vaccination [Vaccination on Day 1]
Systemic events (fever, vomiting, diarrhea, headache, fatigue, chills, new or worsened muscle pain and joint pain) were recorded by participants in the e-diary or by investigators in CRF after vaccination. All systemic events were graded based on CBER toxicity guidelines as Grade 1 (Mild), Grade 2 (Moderate), Grade 3 (Severe) and Grade 4 (potentially life-threatening). In this outcome measure, data is reported as percentage of participants with any systemic events of any grade.
SSB: Percentage of Participants With Systemic Events for up to 7 Days Following Vaccination
Time frame: From Day 1 through Day 7 after study vaccination [Vaccination on Day 1]
Systemic events (fever, vomiting, diarrhea, headache, fatigue, chills, new or worsened muscle pain and joint pain) were recorded by participants in the e-diary or by investigators in CRF after vaccination. All systemic events were graded based on CBER toxicity guidelines as Grade 1 (Mild), Grade 2 (Moderate), Grade 3 (Severe) and Grade 4 (potentially life-threatening). In this outcome measure, data is reported as percentage of participants with any systemic events of any grade.
SSC: Percentage of Participants With Systemic Events for up to 7 Days Following Vaccination
Time frame: From Day 1 through Day 7 after study vaccination [Vaccination on Day 1]
Systemic events (fever, vomiting, diarrhea, headache, fatigue, chills, new or worsened muscle pain and joint pain) were recorded by participants in the e-diary or by investigators in CRF after vaccination. All systemic events were graded based on CBER toxicity guidelines as Grade 1 (Mild), Grade 2 (Moderate), Grade 3 (Severe) and Grade 4 (potentially life-threatening). In this outcome measure, data is reported as percentage of participants with any systemic events of any grade.
SSA: Percentage of Participants With Adverse Events (AEs) From Vaccination Through 4 Weeks After Vaccination
Time frame: From study vaccination on Day 1 through 4 weeks after study vaccination
An AE was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. Only AEs collected by non-systematic assessment (excluding local reactions and systematic events) were included in this outcome measure.
SSB: Percentage of Participants With AEs From Vaccination Through 4 Weeks After Vaccination
Time frame: From study vaccination on Day 1 through 4 weeks after study vaccination
An AE was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. Only AEs collected by non-systematic assessment (excluding local reactions and systematic events) were included in this outcome measure.
SSC: Percentage of Participants With AEs From Vaccination Through 4 Weeks After Vaccination
Time frame: From study vaccination on Day 1 through 4 weeks after study vaccination
An AE was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. Only AEs collected by non-systematic assessment (excluding local reactions and systematic events) were included in this outcome measure.
SSA: Percentage of Participants With SAEs From Vaccination Through 6 Months After Vaccination
Time frame: From study vaccination on Day 1 through 6 months after study vaccination
An SAE was defined as any untoward medical occurrence that, at any dose, met one or more of the following criteria: resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, was a congenital anomaly/birth defect, any other pre-specified criteria in protocol of the study or other important medical event judged by the investigator.
SSB: Percentage of Participants With SAEs From Vaccination Through 6 Months After Vaccination
Time frame: From study vaccination on Day 1 through 6 months after study vaccination
An SAE was defined as any untoward medical occurrence that, at any dose, met one or more of the following criteria: resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, was a congenital anomaly/birth defect, any other pre-specified criteria in protocol of the study or other important medical event judged by the investigator.
SSC: Percentage of Participants With SAEs From Vaccination Through 6 Months After Vaccination
Time frame: From study vaccination on Day 1 through 6 months after study vaccination
An SAE was defined as any untoward medical occurrence that, at any dose, met one or more of the following criteria: resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, was a congenital anomaly/birth defect, any other pre-specified criteria in protocol of the study or other important medical event judged by the investigator.
SSA: Percentage of Participants With Medically Attended Adverse Events (MAEs) From Vaccination Through 6 Months After Vaccination
Time frame: From study vaccination on Day 1 through 6 months after study vaccination
An MAE was defined as a non-serious AE that resulted in an evaluation at a medical facility.
SSB: Percentage of Participants With MAEs From Vaccination Through 6 Months After Vaccination
Time frame: From study vaccination on Day 1 through 6 months after study vaccination
An MAE was defined as a non-serious AE that resulted in an evaluation at a medical facility.
SSC: Percentage of Participants With MAEs From Vaccination Through 6 Months After Vaccination
Time frame: From study vaccination on Day 1 through 6 months after study vaccination
An MAE was defined as a non-serious AE that resulted in an evaluation at a medical facility.
SSA: Percentage of Participants With Newly Diagnosed Chronic Medical Conditions (NDCMCs) From Vaccination Through 6 Months After Vaccination
Time frame: From study vaccination on Day 1 through 6 months after study vaccination
An NDCMC was defined as a disease or medical condition, not previously identified, that was expected to be persistent or otherwise long-lasting in its effects (e.g., asthma).
SSB: Percentage of Participants With NDCMCs From Vaccination Through 6 Months After Vaccination
Time frame: From study vaccination on Day 1 through 6 months after study vaccination
An NDCMC was defined as a disease or medical condition, not previously identified, that was expected to be persistent or otherwise long-lasting in its effects (e.g., asthma).
SSC: Percentage of Participants With NDCMCs From Vaccination Through 6 Months After Vaccination
Time frame: From study vaccination on Day 1 through 6 months after study vaccination
An NDCMC was defined as a disease or medical condition, not previously identified, that was expected to be persistent or otherwise long-lasting in its effects (e.g., asthma).
8 secondary outcomes
SSA: Geometric Mean Titers (GMTs) of Strain-Specific Hemagglutination Inhibition Assay (HAI) Titers at Baseline and 4 Weeks After Vaccination
Time frame: Baseline (before study vaccination on Day 1), 4 weeks after study vaccination
SSA: Geometric Mean Fold Rise (GMFR) of Strain-Specific HAI Titers From Before Vaccination to 4 Weeks After Vaccination
Time frame: From before study vaccination on Day 1 up to 4 weeks after study vaccination
SSA: Percentage of Participants Achieving HAI Seroconversion for Each Strain at 4 Weeks After Vaccination
Time frame: 4 weeks after study vaccination
SSA: Percentage of Participants With HAI Titers >=1:40 For Each Strain at Baseline and 4 Weeks After Vaccination
Time frame: Baseline (before study vaccination on Day 1), 4 weeks after study vaccination
SSB: GMTs of Strain-Specific HAI Titers at Baseline and 4 Weeks After Vaccination
Time frame: Baseline (before study vaccination on Day 1), 4 weeks after study vaccination
SSB: GMFRs of Strain-Specific HAI Titers From Before Vaccination to 4 Weeks After Vaccination
Time frame: From before study vaccination on Day 1 up to 4 weeks after study vaccination
SSB: Percentage of Participants Achieving HAI Seroconversion for Each Strain at 4 Weeks After Vaccination
Time frame: 4 weeks after study vaccination
SSB: Percentage of Participants With HAI Titers >=1:40 For Each Strain at Baseline and 4 Weeks After Vaccination
Time frame: Baseline (before study vaccination on Day 1), 4 weeks after study vaccination
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 12 Jun 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- To obtain contact information for a study center near you, click here.Link provided by the sponsor.
- Individual participant dataSharing planned: Yes. Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical_trials/trial_data_and_results/data_requests.
Related trials for Influenza, Human
Enrolling by invitation
Personalized Ventilator Settings for Patients on ECMO
Acute Respiratory Distress Syndrome (ARDS), Extracorporeal Membrane Oxygenation
RecruitingPhase 2
BPL-1357 Against H1N1 Influenza Virus Challenge
Influenza, Human
Not yet recruitingPhase 1
Safety and Immunogenicity of Chimeric Hemagglutinin mRNA Vaccine Candidates
Influenza
RecruitingPhase 1
pH1N1 Blinded Challenge Study
Influenza
RecruitingPhase 3
A Study to Evaluate the Safety and Efficacy of MK-1406/CD388 for Prevention of Influenza (MK-1406-005/CD388.SQ.3.06)
Influenza
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.
Pfizer CT.gov Call Center study director
Pfizer
32 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1/2 study testing Influenza ModRNA Vaccine and Quadrivalent Influenza Vaccine (QIV) in people with Influenza, Human, run by Pfizer at 32 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 5 inclusion and 4 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 12 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 32 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 combined phase mean?
Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
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 12 Jun 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?
SSA: Percentage of Participants With Local Reactions for up to 7 Days Following Vaccination (time frame: From Day 1 through Day 7 after study vaccination [Vaccination on Day 1]). The study lists 18 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 12 Jun 2026.