GrippePhase 1NCT06179446
A Study to Learn How Safe, Tolerable and Capable of Producing an Immune Response is, a Modified RNA Vaccine Against Pandemic Influenza
A Phase 1 study testing pdmFlu vaccine and Licensed influenza vaccine in people with Grippe and Influenza, run by Pfizer at 3 sites in United States.
Trial summary
The purpose of this study is to learn about the safety and effects of the study vaccine for the possible prevention of influenza. Influenza is a disease that can spread easily from one person to another and cause body aches, fever, cough, and other symptoms. Read more about this study
- Who is it for?
- Ages 18 to 84 yearsHealthy volunteers can take part
- What is being tested?
- pdmFlu vaccine and Licensed influenza vaccine
- Type of treatment
- Vaccines, Injection or infusion
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 157 participants
- Where
- 3 sitesUnited States
- Study dates
- 13 Dec 2023to 23 Sep 2025
- Phase
- Phase 1
- Are there results?
- None posted in the registry
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 84 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Healthy participants who are determined by medical history, physical examination (if required), and clinical judgment of the investigator to be eligible for inclusion in the study.
Who cannot join
- Does not meet seasonal influenza vaccine requirements per cohort.
Trial locations and contacts
3 sites in 1 country.
United States3 sites
Research Centers of America
Hollywood, Florida, 33024
Pfizer Clinical Research Unit - New Haven
New Haven, Connecticut, 06511
NYU Langone Health
New York, New York, 10016
About this study
Official title: A PHASE 1, RANDOMIZED, OBSERVER-BLIND, DOSE-RANGING STUDY TO EVALUATE THE SAFETY, TOLERABILITY, AND IMMUNOGENICITY OF MODIFIED RNA VACCINE CANDIDATES AGAINST PANDEMIC INFLUENZA IN HEALTHY ADULTS
The purpose of this study is to learn about the safety and effects of the study vaccine for the possible prevention of influenza. Influenza is a disease that can spread easily from one person to another and cause body aches, fever, cough, and other symptoms. The study vaccine is called Pandemic Influenza modRNA (pdmFlu) Vaccine.
This study is seeking for participants who are:
Read more
- between the ages of 18 to 49 years old or 65 to 84 years old.
- willing and able to follow with all scheduled visits, treatment plan, laboratory tests, lifestyle changes, and other study procedures.
- healthy as confirmed by medical history, physical examinations, and the study doctor.
- capable of signing informed consent.
Participants will receive either:
- the pdmFlu vaccine,
- a licensed influenza vaccine
- a placebo. A placebo does not have any medicine in it but looks just like the study medicine.
Participants will not know which vaccine they receive. Participants will receive the study vaccines as a single shot in the arm. The study will compare participant experiences to help understand if the pdmFlu vaccine is safe and effective. Participants will take part in this study for up to 13 months. During this time, the participants will receive the study vaccine and take part in follow-up visits.
- Being tested
- pdmFlu vaccine, Placebo, Licensed influenza vaccine
- Keywords
- Flu, Pandemic influenza, RNA vaccine
- Medical subject headings
- Influenza, Human
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
pdmFlu vaccineBiological
Intramuscular injection
PlaceboBiological
Intramuscular injection
Licensed influenza vaccineBiological
Intramuscular injection
| Study group | Role | What they receive |
|---|---|---|
| pdmFlu vaccine 1 | Experimental | Not described Receives: Biological: pdmFlu vaccine |
| pdmFlu vaccine 2 | Experimental | Not described Receives: Biological: pdmFlu vaccine |
| pdmFlu vaccine 3 | Experimental | Not described Receives: Biological: pdmFlu vaccine |
| pdmFlu vaccine 4 | Experimental | Not described Receives: Biological: pdmFlu vaccine |
| pdmFlu vaccine 5 | Experimental | Not described Receives: Biological: pdmFlu vaccine |
| pdmFlu vaccine 6 | Experimental | Not described Receives: Biological: pdmFlu vaccine |
| pdmFlu vaccine 7 | Experimental | Not described Receives: Biological: pdmFlu vaccine |
| pdmFlu vaccine 8 | Experimental | Not described Receives: Biological: pdmFlu vaccine |
| Placebo | Placebo comparator | Not described Receives: Biological: Placebo |
| Licensed influenza vaccine | Active comparator | Not described Receives: Biological: Licensed influenza vaccine |
What is being measured
The primary outcome is the main question the study is designed to answer.
Percentage of participants by age group reporting local reactions
Measured: For 7 days after vaccination
Percentage of participants by age group reporting systemic events
Measured: For 7 days after vaccination
Percentage of participants by age group reporting adverse events
Measured: From vaccination to 4 weeks after each vaccination
Percentage of participants by age group reporting serious adverse events
Measured: From vaccination to 6 months after last vaccination or through the last visit, whichever is longer
Percentage of participants by age group reporting medically attended adverse events
Measured: From vaccination to 6 months after last vaccination or through the last visit, whichever is longer
Percentage of participants by age group with abnormal hematology and chemistry laboratory values
Measured: 1 week, 3 weeks, 6 weeks, 8 weeks and 12 weeks after vaccination 1, 1 week and 4 weeks after vaccination 2, 1 week and 4 weeks after booster vaccination
Percentage of participants by age group with grading shifts in hematology and chemistry laboratory assessments
Measured: Between baseline and 1 week, 3 weeks, 6 weeks, 8 weeks and 12 weeks after vaccination 1, 1 week and 4 weeks after vaccination 2, 1 week and 4 weeks after booster vaccination
Percentage of participants by age group with new clinically significant ECG abnormalities
Measured: 1 week, 3 weeks, 6 weeks, 8 weeks and 12 weeks after vaccination 1, 1 week and 4 weeks after vaccination 2, 1 week and 4 weeks after booster vaccination
Percentage of participants by age group with new troponin I abnormalities
Measured: 1 week, 3 weeks, 6 weeks, 8 weeks and 12 weeks after vaccination 1, 1 week and 4 weeks after vaccination 2, 1 week and 4 weeks after booster vaccination
Secondary outcomes (4)
Geometric mean titers (GMTs) of hemagglutination inhibition (HAI) titers
Measured: At baseline, 1 week, 3 weeks, 6 weeks, 8 weeks and 12 weeks, 16 weeks and 6 months after vaccination 1, 1 week, 4 weeks, 3 months and 6 months after vaccination 2, 1 week, 4 weeks, 12 weeks and 6 months after booster vaccination
Geometric mean fold rise (GMFR) in HAI titers from before vaccination to each subsequent timepoint
Measured: At baseline, 1 week, 3 weeks, 6 weeks, 8 weeks and 12 weeks, 16 weeks and 6 months after vaccination 1, 1 week, 4 weeks, 3 months and 6 months after vaccination 2, 1 week, 4 weeks, 12 weeks and 6 months after booster vaccination
Proportion of participants by age group achieving HAI seroconversion
Measured: At baseline, 1 week, 3 weeks, 6 weeks, 8 weeks and 12 weeks, 16 weeks and 6 months after vaccination 1, 1 week, 4 weeks, 3 months and 6 months after vaccination 2, 1 week, 4 weeks, 12 weeks and 6 months after booster vaccination
Proportion of participants by age group with HAI titer >=1:40
Measured: At baseline, 1 week, 3 weeks, 6 weeks, 8 weeks and 12 weeks, 16 weeks and 6 months after vaccination 1, 1 week, 4 weeks, 3 months and 6 months after vaccination 2, 1 week, 4 weeks, 12 weeks and 6 months after booster vaccination
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Dec 2023
- Study start13 Dec 2023
- Primary completion23 Sep 2025
- Study completion23 Sep 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for GrippeStudies 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
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Sequential
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 157 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
- NCT06179446
- Sponsor's protocol ID
- C5561001
- Other IDs
- NCT06179446
- Status last verified
- Feb 2026
- First submitted
- 12 Dec 2023
- Last updated
- 23 Feb 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No: 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 23 Feb 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A PHASE 1, RANDOMIZED, OBSERVER-BLIND, DOSE-RANGING STUDY TO EVALUATE THE SAFETY, TOLERABILITY, AND IMMUNOGENICITY OF MODIFIED RNA VACCINE CANDIDATES AGAINST PANDEMIC INFLUENZA IN HEALTHY ADULTS
- ClinicalTrials.gov ID
- NCT06179446
- Acronym / sponsor ID
- C5561001
- Keywords
- Flu, Pandemic influenza, RNA vaccine
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 157 participants (actual)
- Lead sponsor
- PfizerIndustry (pharma, biotech, devices)
- Study start
- 13 Dec 2023 (actual)
- Primary completion
- 23 Sep 2025 (actual)
- Study completion
- 23 Sep 2025 (actual)
- First posted
- 21 Dec 2023 (actual)
- Results
- Not posted in the source record
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 about the safety and effects of the study vaccine for the possible prevention of influenza. Influenza is a disease that can spread easily from one person to another and cause body aches, fever, cough, and other symptoms. The study vaccine is called Pandemic Influenza modRNA (pdmFlu) Vaccine.
This study is seeking for participants who are:
- between the ages of 18 to 49 years old or 65 to 84 years old.
- willing and able to follow with all scheduled visits, treatment plan, laboratory tests, lifestyle changes, and other study procedures.
- healthy as confirmed by medical history, physical examinations, and the study doctor.
- capable of signing informed consent.
Participants will receive either:
- the pdmFlu vaccine,
- a licensed influenza vaccine
- a placebo. A placebo does not have any medicine in it but looks just like the study medicine.
Participants will not know which vaccine they receive. Participants will receive the study vaccines as a single shot in the arm. The study will compare participant experiences to help understand if the pdmFlu vaccine is safe and effective. Participants will take part in this study for up to 13 months. During this time, the participants will receive the study vaccine and take part in follow-up visits.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Sequential
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 10
| Arm | Type | Receives |
|---|---|---|
| pdmFlu vaccine 1 | Experimental | Biological: pdmFlu vaccine |
| pdmFlu vaccine 2 | Experimental | Biological: pdmFlu vaccine |
| pdmFlu vaccine 3 | Experimental | Biological: pdmFlu vaccine |
| pdmFlu vaccine 4 | Experimental | Biological: pdmFlu vaccine |
| pdmFlu vaccine 5 | Experimental | Biological: pdmFlu vaccine |
| pdmFlu vaccine 6 | Experimental | Biological: pdmFlu vaccine |
| pdmFlu vaccine 7 | Experimental | Biological: pdmFlu vaccine |
| pdmFlu vaccine 8 | Experimental | Biological: pdmFlu vaccine |
| Placebo | Placebo comparator | Biological: Placebo |
| Licensed influenza vaccine | Active comparator | Biological: Licensed influenza vaccine |
Who may qualify
- Ages
- 18 to 84 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (1 listed)
- Healthy participants who are determined by medical history, physical examination (if required), and clinical judgment of the investigator to be eligible for inclusion in the study.
Key exclusion criteria (1 listed)
- Does not meet seasonal influenza vaccine requirements per cohort.
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 |
|---|---|---|
| pdmFlu vaccineIntramuscular injection | Biological | pdmFlu vaccine 1, pdmFlu vaccine 2, pdmFlu vaccine 3, pdmFlu vaccine 4, pdmFlu vaccine 5, pdmFlu vaccine 6, pdmFlu vaccine 7, pdmFlu vaccine 8 |
| PlaceboIntramuscular injection | Biological | Placebo |
| Licensed influenza vaccineIntramuscular injection | Biological | Licensed influenza vaccine |
Primary outcome
Percentage of participants by age group reporting local reactions
Time frame: For 7 days after vaccination
Percentage of participants by age group reporting systemic events
Time frame: For 7 days after vaccination
Percentage of participants by age group reporting adverse events
Time frame: From vaccination to 4 weeks after each vaccination
Percentage of participants by age group reporting serious adverse events
Time frame: From vaccination to 6 months after last vaccination or through the last visit, whichever is longer
Percentage of participants by age group reporting medically attended adverse events
Time frame: From vaccination to 6 months after last vaccination or through the last visit, whichever is longer
Percentage of participants by age group with abnormal hematology and chemistry laboratory values
Time frame: 1 week, 3 weeks, 6 weeks, 8 weeks and 12 weeks after vaccination 1, 1 week and 4 weeks after vaccination 2, 1 week and 4 weeks after booster vaccination
Percentage of participants by age group with grading shifts in hematology and chemistry laboratory assessments
Time frame: Between baseline and 1 week, 3 weeks, 6 weeks, 8 weeks and 12 weeks after vaccination 1, 1 week and 4 weeks after vaccination 2, 1 week and 4 weeks after booster vaccination
Percentage of participants by age group with new clinically significant ECG abnormalities
Time frame: 1 week, 3 weeks, 6 weeks, 8 weeks and 12 weeks after vaccination 1, 1 week and 4 weeks after vaccination 2, 1 week and 4 weeks after booster vaccination
Percentage of participants by age group with new troponin I abnormalities
Time frame: 1 week, 3 weeks, 6 weeks, 8 weeks and 12 weeks after vaccination 1, 1 week and 4 weeks after vaccination 2, 1 week and 4 weeks after booster vaccination
4 secondary outcomes
Geometric mean titers (GMTs) of hemagglutination inhibition (HAI) titers
Time frame: At baseline, 1 week, 3 weeks, 6 weeks, 8 weeks and 12 weeks, 16 weeks and 6 months after vaccination 1, 1 week, 4 weeks, 3 months and 6 months after vaccination 2, 1 week, 4 weeks, 12 weeks and 6 months after booster vaccination
Geometric mean fold rise (GMFR) in HAI titers from before vaccination to each subsequent timepoint
Time frame: At baseline, 1 week, 3 weeks, 6 weeks, 8 weeks and 12 weeks, 16 weeks and 6 months after vaccination 1, 1 week, 4 weeks, 3 months and 6 months after vaccination 2, 1 week, 4 weeks, 12 weeks and 6 months after booster vaccination
Proportion of participants by age group achieving HAI seroconversion
Time frame: At baseline, 1 week, 3 weeks, 6 weeks, 8 weeks and 12 weeks, 16 weeks and 6 months after vaccination 1, 1 week, 4 weeks, 3 months and 6 months after vaccination 2, 1 week, 4 weeks, 12 weeks and 6 months after booster vaccination
Proportion of participants by age group with HAI titer >=1:40
Time frame: At baseline, 1 week, 3 weeks, 6 weeks, 8 weeks and 12 weeks, 16 weeks and 6 months after vaccination 1, 1 week, 4 weeks, 3 months and 6 months after vaccination 2, 1 week, 4 weeks, 12 weeks and 6 months after booster vaccination
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 23 Feb 2026.
- To obtain contact information for a study center near you, click here.Link provided by the sponsor.
- Individual participant dataSharing planned: No. 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.
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
3 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1 study testing pdmFlu vaccine and Licensed influenza vaccine in people with Grippe and Influenza, run by Pfizer at 3 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 1 inclusion and 1 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 23 Feb 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 3 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. Some participants in this study may receive a placebo. 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 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.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
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?
Percentage of participants by age group reporting local reactions (time frame: For 7 days after vaccination). The study lists 9 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 23 Feb 2026; AzTrials last refreshed its copy on 28 Oct 2026.