CompletedNCT06361875Updated Aug 4, 2026Results posted

A Study to Investigate the Safety and Immunogenicity of the Quadrivalent Influenza mRNA Vaccines in Adults Aged 18 Years and Above

A Phase 1/2 interventional study of Quadrivalent Influenza mRNA Vaccine MRT5421 and Quadrivalent Influenza mRNA Vaccine MRT5424 in Influenza Immunization and Healthy Volunteers, sponsored by Sanofi Pasteur, a Sanofi Company. Completed at 13 sites in 3 countries. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-08-04.

Sponsored by Sanofi Pasteur, a Sanofi Company (part of Sanofi) · Phase 1/2, Interventional, and Prevention

Phase: Phase 1/2
Study type: Interventional
Enrollment: 908
Allocation: Randomized
Ages: 18 Years and older
Sex: All

Study summary

The purpose of this study was to evaluate the safety and immunogenicity of a single intramuscular (IM) injection of different formulations of Quadrivalent Influenza Vaccine (QIV) messenger ribonucleic acid (mRNA) (MRT5421, MRT5424, and MRT5429) compared to an active control (QIV- standard dose (SD), QIV- high dose (HD) [adults ≥ 65 years of age only], or quadrivalent recombinant influenza vaccine (RIV4)) in adults 18 years of age and older.

Read the detailed description

Study duration per participant was approximately 12 months.

Treatment duration: 1 injection of one of the 7 QIV mRNA or one of the controls
Dose escalation with sequential enrollment

Conditions studied

Influenza Immunization
Healthy Volunteers

Browse trials for

Influenza, Human 2,356

In context

Influenza, Human

2,356 studies on the registry are indexed under Influenza, Human; 184 are open to participants now.

This study's enrollment of 908 is above the median of 227 across 1,957 interventional studies indexed under Influenza, Human.

Browse Influenza, Human studies →

Lead sponsor

Sanofi Pasteur, a Sanofi Company is the lead sponsor of 374 studies on the registry; 4 are open to participants now.

Of its 94 completed or terminated interventional studies of FDA-regulated products, 73 (78%) have results posted.

First submitted after Sanofi Pasteur became part of Sanofi.

Browse Sanofi Pasteur studies →All Sanofi studies →

Counted across the registry records on this site, refreshed daily.

Who can participate

Ages eligible: 18 Years and older
Sexes eligible: All
Accepts healthy volunteers: Yes

Eligibility criteria

Inclusion Criteria:

Aged from 18 years on the day of inclusion or aged from 21 years on the days of inclusion, depending on the countries.
A female participant was eligible to participate if she was not pregnant or breastfeeding and one of the following conditions applied:
- Was of non-. To be considered of non-childbearing potential, a female must of been for at least 1 year, or surgically sterile OR
- Was of childbearing potential and agreed to use an effective method or abstinence from at least 4 weeks prior to study intervention administration until at least 12 weeks after study intervention administration.
A female participant of childbearing potential must of had a negative highly sensitive pregnancy test (urine or serum as required by local regulation) within 8 hours before the 1st dose of study intervention

Exclusion Criteria: Participants were excluded from the study if any of the following criteria applied:

Known or suspected congenital or acquired immunodeficiency; or receipt of therapy, such as anti-cancer chemotherapy or radiation therapy, within the preceding 6 months; or long-term systemic therapy (prednisone or equivalent for more than 2 consecutive weeks within the past 3 months)
Known systemic to any of the study intervention components (eg, polyethylene glycol, polysorbate); history of a life-threatening reaction to the study interventions used in the study or to a product containing any of the same substances; any allergic reaction (eg, anaphylaxis) after administration of mRNA vaccine
Previous history of myocarditis, pericarditis, and / or myopericarditis
Known history of previous episodes of Gillian-Barre Syndrome (GBS), neuritis (including Bell's palsy), convulsions, encephalitis, transverse myelitis, and vasculitis
Participants with an that is consistent with possible myocarditis or pericarditis or, in the opinion of the investigator, demonstrates abnormalities that may affect participant safety or study results
Self-reported thrombocytopenia, contraindicating Intramuscular vaccination based on Investigator's judgment
Bleeding disorder, or receipt of anticoagulants in the 3 weeks preceding inclusion, contraindicating Intramuscular vaccination based on Investigator's judgment
Chronic illness that, in the opinion of the Investigator, was at a stage where it might have interfered with study conduct or completion
Moderate or severe acute illness / infection (according to Investigator's judgment) or febrile illness (temperature ≥ 38.0°C [≥ 100.4°F]) on the day of vaccination. A prospective participant was not included in the study until the condition was resolved or the febrile event subsided
Participant who had acute infection symptoms or a positive SARS-CoV-2 RT-PCR or antigen test in the past 10 days prior to the 1st visit (V01)
Receipt of any vaccine in the 4 weeks preceding study intervention administration or planned receipt of any vaccine in the 4 weeks following study intervention administration
Receipt of immune globulins, blood or blood-derived products in the past 3 months
Previous vaccination against influenza in the previous 6 months with an or marketed vaccine
Receipt of any mRNA vaccine/product in the 2 months preceding study intervention administration

NOTE: The above information was not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.

Terms in these criteria, in plain language(9)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

Childbearing potential

Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).

Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.

Postmenopausal

Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).

Contraception

Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.

Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.

Immunosuppression

A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.

Read whether the line is about a condition or about medicines, and which medicines and doses it means.

Corticosteroids (steroids)

Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.

Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.

Hypersensitivity

An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.

ECG (electrocardiogram)

A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.

Clinically significant

Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.

Investigational drug or device

A drug or device being studied in a clinical trial.

It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.

Study design

Phase: Phase 1 / Phase 2
Primary purpose: Prevention
Allocation: Randomized
Intervention model: Parallel assignment
Masking: Triple (Participant, Investigator, Outcomes assessor)
Enrollment: 908 participants (actual)

Study arms

Experimental
Quadrivalent Influenza mRNA Vaccine MRT5421 Dose 1
participants received a single dose of QIV mRNA vaccine MRT5421
Biological: Quadrivalent Influenza mRNA Vaccine MRT5421
Experimental
Quadrivalent Influenza mRNA Vaccine MRT5429 Dose 1
participants received a single dose of QIV mRNA vaccine MRT5429
Biological: Quadrivalent Influenza mRNA Vaccine MRT5429
Experimental
Quadrivalent Influenza mRNA Vaccine MRT5429 Dose 2
participants received a single dose of QIV mRNA vaccine MRT5429
Biological: Quadrivalent Influenza mRNA Vaccine MRT5429
Experimental
Quadrivalent Influenza mRNA Vaccine MRT5429 Dose 3
participants received a single dose of QIV mRNA vaccine MRT5429
Biological: Quadrivalent Influenza mRNA Vaccine MRT5429
Experimental
Quadrivalent Influenza mRNA Vaccine MRT5429 Dose 4
participants received a single dose of QIV mRNA vaccine MRT5429
Biological: Quadrivalent Influenza mRNA Vaccine MRT5429
Experimental
Quadrivalent Influenza mRNA Vaccine MRT5424 Dose 1
participants received a single dose of QIV mRNA vaccine MRT5424
Biological: Quadrivalent Influenza mRNA Vaccine MRT5424
Experimental
Quadrivalent Influenza mRNA Vaccine MRT5424 Dose 2
participants received a single dose of QIV mRNA vaccine MRT5424
Biological: Quadrivalent Influenza mRNA Vaccine MRT5424
Active comparator
Quadrivalent Influenza SD Vaccine
participants received a single dose of QIV-SD vaccine
Biological: Quadrivalent Influenza Standard Dose Vaccine
Active comparator
Quadrivalent Influenza HD Vaccine
participants received a single dose of QIV -HD vaccine (for adults ≥ 65 years of age only)
Biological: Quadrivalent Influenza High-Dose Vaccine
Active comparator
Quadrivalent Influenza RIV4 Vaccine
participants received a single dose of RIV4 vaccine
Biological: Quadrivalent Recombinant Influenza Vaccine

Interventions

BiologicalQuadrivalent Influenza mRNA Vaccine MRT5421
Pharmaceutical form:solution in a vial-Route of administration:Intramuscular injection
BiologicalQuadrivalent Influenza mRNA Vaccine MRT5424
Pharmaceutical form:solution in a vial-Route of administration:Intramuscular injection
BiologicalQuadrivalent Influenza mRNA Vaccine MRT5429
Pharmaceutical form:solution in a vial-Route of administration:Intramuscular Injection
BiologicalQuadrivalent Influenza Standard Dose Vaccine
Pharmaceutical form: suspension for injection in prefilled syringe -Route of administration:Intramuscular injection
Also known as: Fluzone Qudrivalent®
BiologicalQuadrivalent Influenza High-Dose Vaccine
Pharmaceutical form:suspension for injection in pre filled syringe -Route of administration:Intramuscular injection
Also known as: Fluzone High-Dose Quadrivalent®
BiologicalQuadrivalent Recombinant Influenza Vaccine
Pharmaceutical form:suspension for injection in pre filled syringe-Route of administration:Intramuscular injection
Also known as: Flublok Quadrivalent®

What researchers measure

Primary outcomes

Number of Participants With Immediate Unsolicited Systemic Adverse Events (AEs) After Vaccine Administration
An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study vaccine, whether or not considered related to the study vaccine. An unsolicited AE is an observed AE that does not fulfill the conditions of solicited reactions, that is, pre-listed in the case report form in terms of diagnosis and onset window post-vaccination. Systemic AEs are all AEs that were not injection or administration site reactions. Immediate events are recorded to capture medically relevant unsolicited systemic AEs which occur within the first 30 minutes after vaccination.
Time frame: Within 30 minutes after vaccine administration on Day 1
Number of Participants With Solicited Injection Site Reactions After Vaccine Administration
An adverse reaction (AR) is any noxious and unintended response to a study vaccine related to any dose. Solicited injection site reactions are reactions at and around the injection site of the vaccine observed and reported under the conditions (nature and onset) pre-listed in the protocol and case report form.
Time frame: Within 7 days after vaccine administration on Day 1
Number of Participants With Solicited Systemic Reactions After Vaccine Administration
An AR is any noxious and unintended response to a study vaccine related to any dose. Solicited systemic reactions are systemic AEs observed and reported under the conditions (nature and onset) pre-listed in the protocol and case report form.
Time frame: Within 7 days after vaccine administration on Day 1
Number of Participants With Unsolicited Adverse Events After Vaccine Administration
An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study vaccine, whether or not considered related to the study vaccine. An unsolicited AE is an observed AE that does not fulfill the conditions of solicited reactions, that is, pre-listed in the case report form in terms of diagnosis and onset window post-vaccination.
Time frame: Within 28 days after vaccine administration on Day 1
Number of Participants With Medically Attended Adverse Events (MAAEs)
An MAAE is a new onset or a worsening of a condition that prompts the participant or participant's parent/legally acceptable representative to seek unplanned medical advice at a physician's office or emergency department.
Time frame: Within 180 days after vaccine administration on Day 1
Number of Participants With Serious Adverse Events (SAEs) and Adverse Event of Special Interest (AESIs)
An SAE is any untoward medical occurrence that at any dose results in death or is life-threatening or requires inpatient hospitalization or prolongation of existing hospitalization or results in persistent or significant disability/incapacity or is a congenital anomaly/birth defect or is an important medical event. An AESI (serious or non-serious) is 1 of scientific and medical concern specific to the Sponsor's study vaccine or program, for which ongoing monitoring and rapid communication by the investigator to the Sponsor can be appropriate. The AESIs was defined as anaphylactic reactions (including bronchospasms, and laryngeal spasms), Guillain-Barré syndrome, neuritis (including Bell's palsy), myocarditis, pericarditis, myopericarditis and vasculitis.
Time frame: From the vaccine administration (Day 1) until 12 months after vaccine administration, approximately 366 days
Number of Participants With Abnormal Biological Test Results
Blood samples were collected for the assessment of abnormal hematology and clinical chemistry parameters. Only participants with outside the normal range hematology and clinical chemistry parameters are reported.
Time frame: Within 8 days after vaccine administration on Day 1
Geometric Mean of Hemagglutination Inhibition (HAI) Antibody (Ab) Titer at Day 1
The HAI Ab was measured by hemagglutinin inhibition using quality control sera (sheep, ferret and/or human sera) measurement method. The 95% confidence interval (CI) was based on the Clopper-Pearson method.
Time frame: Day 1
Geometric Mean of Hemagglutination Inhibition Antibody Titer at Day 29
The HAI Ab was measured by hemagglutinin inhibition using quality control sera (sheep, ferret and/or human sera) measurement method. The 95% CI was based on the Clopper-Pearson method.
Time frame: Day 29
Percentage of Participants With Detectable Hemagglutination Inhibition Antibody Titer >=1:10 at Day 1
The HAI Ab was measured by hemagglutinin inhibition using quality control sera (sheep, ferret and/or human sera) measurement method. The 95% CI for the single percentage was based on the Clopper-Pearson method. The percentages are rounded off to the tenth decimal place.
Time frame: Day 1
Percentage of Participants With Detectable Hemagglutination Inhibition Antibody Titer >=1:10 at Day 29
The HAI Ab was measured by hemagglutinin inhibition using quality control sera (sheep, ferret and/or human sera) measurement method. The 95% CI for the single percentage was based on the Clopper-Pearson method. The percentages are rounded off to the tenth decimal place.
Time frame: Day 29
Geometric Mean Ratio of Hemagglutination Inhibition Antibody Titer at Day 29
The HAI Ab was measured by hemagglutinin inhibition using quality control sera (sheep, ferret and/or human sera) measurement method. The geometric mean ratio of antibody titer at post-vaccination over pre-vaccination is reported. The 95% CI was based on the Clopper-Pearson method.
Time frame: Days 1 and 29
Percentage of Participants With Seroconversion of Hemagglutination Inhibition Antibody Titer at Day 29
The seroconversion was defined as titer \<10 on Day 1 and post-injection titer \>=40 on Day 29; or defined as titer \>=10 on Day 1 and a \>=4-fold increase in titer on Day 29. The 95% CI for the single percentage was based on the Clopper-Pearson method. The percentages are rounded off to the tenth decimal place.
Time frame: Day 29
Percentage of Participants With Hemagglutination Inhibition Antibody Titer >=1:40 at Day 29
The HAI Ab was measured by hemagglutinin inhibition using quality control sera (sheep, ferret and/or human sera) measurement method. The 95% CI for the single percentage was based on the Clopper-Pearson method. The percentages are rounded off to the tenth decimal place.
Time frame: Day 29
Percentage of Participants With >=2 and >=4 Fold Increase in Hemagglutination Inhibition Antibody Titer at Day 29
The HAI Ab was measured by hemagglutinin inhibition using quality control sera (sheep, ferret and/or human sera) measurement method. The 95% CI for the single percentage was based on the Clopper-Pearson method. The percentages are rounded off to the tenth decimal place.
Time frame: Days 1 and 29

Secondary outcomes

Geometric Mean of Neutralization Test (NT) Antibody Titer at Days 1 and 29
The NT Ab was planned to be measured using seroneutralization (SN) measurement method. The 95% CI was planned to be calculated using the Clopper-Pearson method.
Time frame: Days 1 and 29
Geometric Mean Ratio of Neutralization Test Antibody Titer at Day 29
The NT Ab was planned to be measured using SN measurement method. The geometric mean ratio of antibody titer at post-vaccination over pre-vaccination was planned to be reported. The 95% CI was planned to be calculated using the Clopper-Pearson method.
Time frame: Days 1 and 29
Percentage of Participants With >=2 and >=4 Fold Increase in Neutralization Test Antibody Titer at Day 29
The NT Ab was planned to be measured using SN measurement method. The 95% CI for the single percentage was planned to be calculated using the Clopper-Pearson method.
Time frame: Days 1 and 29

Results

Posted Aug 4, 2026

Limitations and caveats

Due to internal project decisions made during the study, neutralizing antibody data was not collected. Therefore, no analysis was conducted for secondary outcome measures.

Participant flow

The study was conducted at 19 centers in 2 countries from 01 April 2024 to 09 June 2025. QIV mRNA= Quadrivalent influenza modified messenger ribonucleic acid vaccine; QIV-SD= Standard dose quadrivalent influenza vaccine; RIV4= Quadrivalent recombinant influenza vaccine; QIV-HD= High dose quadrivalent influenza vaccine.

Participant flow — Overall Study
Milestone	QIV mRNA LNP 1: 30 mcg	QIV mRNA LNP 1: 96 mcg	QIV mRNA LNP 1: 132 mcg	QIV mRNA LNP 1: 192 mcg	QIV mRNA LNP 2: 96 mcg	QIV mRNA LNP 2: 192 mcg	QIV mRNA LNP 3: 192 mcg	QIV-SD	RIV4	QIV-HD
Started	28	121	119	120	120	27	75	119	119	60
Completed	26	117	112	119	115	25	71	114	110	60
Not completed	2	4	7	1	5	2	4	5	9	0
Withdrew: Protocol deviation	0	2	2	0	1	0	1	2	4	0
Withdrew: Withdrawal by subject	1	1	3	0	3	2	1	2	3	0
Withdrew: Lost to follow-up	1	1	2	1	0	0	2	1	2	0
Withdrew: Other	0	0	0	0	1	0	0	0	0	0

Outcome measures

PrimaryNumber of Participants With Immediate Unsolicited Systemic Adverse Events (AEs) After Vaccine Administration

An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study vaccine, whether or not considered related to the study vaccine. An unsolicited AE is an observed AE that does not fulfill the conditions of solicited reactions, that is, pre-listed in the case report form in terms of diagnosis and onset window post-vaccination. Systemic AEs are all AEs that were not injection or administration site reactions. Immediate events are recorded to capture medically relevant unsolicited systemic AEs which occur within the first 30 minutes after vaccination.

Time frame:: Within 30 minutes after vaccine administration on Day 1
Reported as:: Count of participants · Participants

Number of Participants With Immediate Unsolicited Systemic Adverse Events (AEs) After Vaccine Administration
Participants	QIV mRNA LNP 1: 30 mcg	QIV mRNA LNP 1: 96 mcg	QIV mRNA LNP 1: 132 mcg	QIV mRNA LNP 1: 192 mcg	QIV mRNA LNP 2: 96 mcg	QIV mRNA LNP 2: 192 mcg	QIV mRNA LNP 3: 192 mcg	QIV-SD	RIV4	QIV-HD
Number of Participants With Immediate Unsolicited Systemic Adverse Events (AEs) After Vaccine Administration	1	1	1	0	1	0	0	0	0	0

PrimaryNumber of Participants With Solicited Injection Site Reactions After Vaccine Administration

An adverse reaction (AR) is any noxious and unintended response to a study vaccine related to any dose. Solicited injection site reactions are reactions at and around the injection site of the vaccine observed and reported under the conditions (nature and onset) pre-listed in the protocol and case report form.

Time frame:: Within 7 days after vaccine administration on Day 1
Reported as:: Count of participants · Participants

Number of Participants With Solicited Injection Site Reactions After Vaccine Administration
Participants	QIV mRNA LNP 1: 30 mcg	QIV mRNA LNP 1: 96 mcg	QIV mRNA LNP 1: 132 mcg	QIV mRNA LNP 1: 192 mcg	QIV mRNA LNP 2: 96 mcg	QIV mRNA LNP 2: 192 mcg	QIV mRNA LNP 3: 192 mcg	QIV-SD	RIV4	QIV-HD
Number of Participants With Solicited Injection Site Reactions After Vaccine Administration	11	71	76	79	74	17	50	24	18	13

PrimaryNumber of Participants With Solicited Systemic Reactions After Vaccine Administration

An AR is any noxious and unintended response to a study vaccine related to any dose. Solicited systemic reactions are systemic AEs observed and reported under the conditions (nature and onset) pre-listed in the protocol and case report form.

Time frame:: Within 7 days after vaccine administration on Day 1
Reported as:: Count of participants · Participants

Number of Participants With Solicited Systemic Reactions After Vaccine Administration
Participants	QIV mRNA LNP 1: 30 mcg	QIV mRNA LNP 1: 96 mcg	QIV mRNA LNP 1: 132 mcg	QIV mRNA LNP 1: 192 mcg	QIV mRNA LNP 2: 96 mcg	QIV mRNA LNP 2: 192 mcg	QIV mRNA LNP 3: 192 mcg	QIV-SD	RIV4	QIV-HD
Number of Participants With Solicited Systemic Reactions After Vaccine Administration	15	58	71	73	60	18	48	21	17	16

PrimaryNumber of Participants With Unsolicited Adverse Events After Vaccine Administration

Time frame:: Within 28 days after vaccine administration on Day 1
Reported as:: Count of participants · Participants

Number of Participants With Unsolicited Adverse Events After Vaccine Administration
Participants	QIV mRNA LNP 1: 30 mcg	QIV mRNA LNP 1: 96 mcg	QIV mRNA LNP 1: 132 mcg	QIV mRNA LNP 1: 192 mcg	QIV mRNA LNP 2: 96 mcg	QIV mRNA LNP 2: 192 mcg	QIV mRNA LNP 3: 192 mcg	QIV-SD	RIV4	QIV-HD
Number of Participants With Unsolicited Adverse Events After Vaccine Administration	3	30	26	26	32	11	20	15	14	10

PrimaryNumber of Participants With Medically Attended Adverse Events (MAAEs)

An MAAE is a new onset or a worsening of a condition that prompts the participant or participant's parent/legally acceptable representative to seek unplanned medical advice at a physician's office or emergency department.

Time frame:: Within 180 days after vaccine administration on Day 1
Reported as:: Count of participants · Participants

Number of Participants With Medically Attended Adverse Events (MAAEs)
Participants	QIV mRNA LNP 1: 30 mcg	QIV mRNA LNP 1: 96 mcg	QIV mRNA LNP 1: 132 mcg	QIV mRNA LNP 1: 192 mcg	QIV mRNA LNP 2: 96 mcg	QIV mRNA LNP 2: 192 mcg	QIV mRNA LNP 3: 192 mcg	QIV-SD	RIV4	QIV-HD
Number of Participants With Medically Attended Adverse Events (MAAEs)	2	10	12	6	10	2	7	12	13	8

PrimaryNumber of Participants With Serious Adverse Events (SAEs) and Adverse Event of Special Interest (AESIs)

An SAE is any untoward medical occurrence that at any dose results in death or is life-threatening or requires inpatient hospitalization or prolongation of existing hospitalization or results in persistent or significant disability/incapacity or is a congenital anomaly/birth defect or is an important medical event. An AESI (serious or non-serious) is 1 of scientific and medical concern specific to the Sponsor's study vaccine or program, for which ongoing monitoring and rapid communication by the investigator to the Sponsor can be appropriate. The AESIs was defined as anaphylactic reactions (including bronchospasms, and laryngeal spasms), Guillain-Barré syndrome, neuritis (including Bell's palsy), myocarditis, pericarditis, myopericarditis and vasculitis.

Time frame:: From the vaccine administration (Day 1) until 12 months after vaccine administration, approximately 366 days
Reported as:: Count of participants · Participants

Number of Participants With Serious Adverse Events (SAEs) and Adverse Event of Special Interest (AESIs)
Participants	QIV mRNA LNP 1: 30 mcg	QIV mRNA LNP 1: 96 mcg	QIV mRNA LNP 1: 132 mcg	QIV mRNA LNP 1: 192 mcg	QIV mRNA LNP 2: 96 mcg	QIV mRNA LNP 2: 192 mcg	QIV mRNA LNP 3: 192 mcg	QIV-SD	RIV4	QIV-HD
Any SAE	0	4	2	3	0	0	1	2	4	1
Any AESI	0	0	0	0	0	0	0	0	0	0

PrimaryNumber of Participants With Abnormal Biological Test Results

Blood samples were collected for the assessment of abnormal hematology and clinical chemistry parameters. Only participants with outside the normal range hematology and clinical chemistry parameters are reported.

Time frame:: Within 8 days after vaccine administration on Day 1
Reported as:: Count of participants · Participants

Number of Participants With Abnormal Biological Test Results
Participants	QIV mRNA LNP 1: 30 mcg	QIV mRNA LNP 1: 96 mcg	QIV mRNA LNP 1: 132 mcg	QIV mRNA LNP 1: 192 mcg	QIV mRNA LNP 2: 96 mcg	QIV mRNA LNP 2: 192 mcg	QIV mRNA LNP 3: 192 mcg	QIV-SD	RIV4	QIV-HD
Hemoglobin	4	13	18	22	17	7	13	16	17	9
White blood cell	0	9	10	6	7	4	3	7	6	5
Neutrophils	0	7	5	4	9	3	2	9	6	1
Eosinophils	0	3	2	5	5	1	6	7	4	1
Basophils	1	1	3	4	3	1	0	2	1	0
Lymphocytes	1	4	13	6	8	0	5	6	2	7
Monocytes	0	13	14	12	14	1	12	11	13	4
Platelets	1	7	3	7	7	2	6	3	8	3
Erythrocytes	5	14	15	14	20	5	6	20	15	16
Creatinine	3	14	12	21	12	7	7	8	16	7
C-reactive protein	2	22	24	15	24	4	17	23	23	9
Aspartate aminotransferase	2	18	24	20	22	3	13	25	18	6
Alanine aminotransferase	3	6	11	4	6	0	3	6	5	3
Total bilirubin	1	6	9	9	9	2	1	6	4	0
Direct bilirubin	0	6	7	6	6	1	0	5	7	2
Troponin I	0	3	7	3	8	1	5	8	3	0

PrimaryGeometric Mean of Hemagglutination Inhibition (HAI) Antibody (Ab) Titer at Day 1

The HAI Ab was measured by hemagglutinin inhibition using quality control sera (sheep, ferret and/or human sera) measurement method. The 95% confidence interval (CI) was based on the Clopper-Pearson method.

Time frame:: Day 1
Reported as:: Geometric mean · titer

Geometric Mean of Hemagglutination Inhibition (HAI) Antibody (Ab) Titer at Day 1
titer	QIV mRNA LNP 1: 30 mcg	QIV mRNA LNP 1: 96 mcg	QIV mRNA LNP 1: 132 mcg	QIV mRNA LNP 1: 192 mcg	QIV mRNA LNP 2: 96 mcg	QIV mRNA LNP 2: 192 mcg	QIV mRNA LNP 3: 192 mcg	QIV-SD	RIV4	QIV-HD
HAI homologous strain A/H1N1	84.1 (46.0 to 154)	86.2 (65.4 to 114)	102 (76.4 to 136)	86.2 (64.1 to 116)	78.6 (59.8 to 103)	98.2 (51.1 to 189)	99.9 (72.7 to 137)	102 (78.0 to 132)	106 (79.7 to 140)	80.9 (57.0 to 115)
HAI homologous strain A/H3N2	50.0 (27.2 to 91.8)	50.1 (36.7 to 68.5)	53.3 (39.3 to 72.4)	49.8 (37.3 to 66.5)	45.0 (33.8 to 59.9)	33.4 (16.5 to 67.8)	60.1 (41.6 to 86.8)	43.4 (32.1 to 58.7)	55.4 (41.1 to 74.7)	47.0 (32.8 to 67.3)
HAI homologous strain B/Yamagata-lineage	244 (162 to 367)	179 (142 to 225)	278 (222 to 348)	211 (169 to 264)	192 (154 to 240)	196 (125 to 310)	245 (188 to 319)	182 (140 to 236)	209 (167 to 262)	186 (137 to 252)
HAI homologous strain B/Victoria-lineage	122 (74.5 to 199)	86.7 (65.9 to 114)	91.6 (69.3 to 121)	94.6 (72.1 to 124)	77.7 (59.3 to 102)	65.1 (41.6 to 102)	78.5 (57.0 to 108)	76.4 (57.9 to 101)	77.7 (58.9 to 103)	139 (98.0 to 198)

PrimaryGeometric Mean of Hemagglutination Inhibition Antibody Titer at Day 29

The HAI Ab was measured by hemagglutinin inhibition using quality control sera (sheep, ferret and/or human sera) measurement method. The 95% CI was based on the Clopper-Pearson method.

Time frame:: Day 29
Reported as:: Geometric mean · titer

Geometric Mean of Hemagglutination Inhibition Antibody Titer at Day 29
titer	QIV mRNA LNP 1: 30 mcg	QIV mRNA LNP 1: 96 mcg	QIV mRNA LNP 1: 132 mcg	QIV mRNA LNP 1: 192 mcg	QIV mRNA LNP 2: 96 mcg	QIV mRNA LNP 2: 192 mcg	QIV mRNA LNP 3: 192 mcg	QIV-SD	RIV4	QIV-HD
HAI homologous strain A/H1N1	362 (235 to 558)	357 (283 to 451)	447 (362 to 553)	396 (317 to 495)	558 (441 to 706)	640 (348 to 1176)	486 (385 to 613)	314 (252 to 393)	493 (395 to 615)	221 (160 to 305)
HAI homologous strain A/H3N2	226 (126 to 407)	320 (247 to 414)	369 (286 to 477)	445 (350 to 566)	507 (396 to 649)	503 (278 to 910)	391 (281 to 542)	232 (181 to 298)	621 (476 to 811)	216 (150 to 311)
HAI homologous strain B/Yamagata-lineage	390 (262 to 582)	381 (310 to 468)	603 (499 to 728)	494 (409 to 596)	585 (493 to 695)	453 (306 to 668)	524 (417 to 658)	505 (405 to 629)	651 (539 to 787)	427 (325 to 562)
HAI homologous strain B/Victoria-lineage	256 (174 to 377)	232 (183 to 295)	242 (191 to 306)	302 (241 to 379)	269 (214 to 338)	173 (95.7 to 314)	270 (195 to 373)	371 (302 to 455)	320 (256 to 400)	520 (391 to 692)

PrimaryPercentage of Participants With Detectable Hemagglutination Inhibition Antibody Titer >=1:10 at Day 1

The HAI Ab was measured by hemagglutinin inhibition using quality control sera (sheep, ferret and/or human sera) measurement method. The 95% CI for the single percentage was based on the Clopper-Pearson method. The percentages are rounded off to the tenth decimal place.

Time frame:: Day 1
Reported as:: Number · percentage of participants

Percentage of Participants With Detectable Hemagglutination Inhibition Antibody Titer >=1:10 at Day 1
percentage of participants	QIV mRNA LNP 1: 30 mcg	QIV mRNA LNP 1: 96 mcg	QIV mRNA LNP 1: 132 mcg	QIV mRNA LNP 1: 192 mcg	QIV mRNA LNP 2: 96 mcg	QIV mRNA LNP 2: 192 mcg	QIV mRNA LNP 3: 192 mcg	QIV-SD	RIV4	QIV-HD
HAI homologous strain A/H1N1	92.9 (76.5 to 99.1)	92.5 (86.2 to 96.5)	90.7 (83.9 to 95.3)	87.5 (80.2 to 92.8)	91.5 (84.8 to 95.8)	96.3 (81.0 to 99.9)	96.0 (88.8 to 99.2)	94.1 (88.3 to 97.6)	94.1 (88.3 to 97.6)	98.3 (91.1 to 100)
HAI homologous strain A/H3N2	89.3 (71.8 to 97.7)	83.3 (75.4 to 89.5)	85.6 (77.9 to 91.4)	83.3 (75.4 to 89.5)	84.6 (76.8 to 90.6)	74.1 (53.7 to 88.9)	85.3 (75.3 to 92.4)	79.8 (71.5 to 86.6)	84.0 (76.2 to 90.1)	91.7 (81.6 to 97.2)
HAI homologous strain B/Yamagata-lineage	100 (87.7 to 100)	98.3 (94.1 to 99.8)	98.3 (94.0 to 99.8)	100 (97.0 to 100)	98.3 (94.0 to 99.8)	96.3 (81.0 to 99.9)	100 (95.2 to 100)	98.3 (94.1 to 99.8)	100 (96.9 to 100)	98.3 (91.1 to 100)
HAI homologous strain B/Victoria-lineage	100 (87.7 to 100)	95.8 (90.5 to 98.6)	94.1 (88.2 to 97.6)	95.0 (89.4 to 98.1)	94.0 (88.1 to 97.6)	100 (87.2 to 100)	96.0 (88.8 to 99.2)	93.3 (87.2 to 97.1)	93.3 (87.2 to 97.1)	95.0 (86.1 to 99.0)

PrimaryPercentage of Participants With Detectable Hemagglutination Inhibition Antibody Titer >=1:10 at Day 29

Time frame:: Day 29
Reported as:: Number · percentage of participants

Percentage of Participants With Detectable Hemagglutination Inhibition Antibody Titer >=1:10 at Day 29
percentage of participants	QIV mRNA LNP 1: 30 mcg	QIV mRNA LNP 1: 96 mcg	QIV mRNA LNP 1: 132 mcg	QIV mRNA LNP 1: 192 mcg	QIV mRNA LNP 2: 96 mcg	QIV mRNA LNP 2: 192 mcg	QIV mRNA LNP 3: 192 mcg	QIV-SD	RIV4	QIV-HD
HAI homologous strain A/H1N1	100 (87.7 to 100)	100 (96.9 to 100)	100 (96.9 to 100)	100 (97.0 to 100)	100 (96.9 to 100)	100 (86.8 to 100)	100 (95.1 to 100)	100 (96.9 to 100)	99.1 (95.3 to 100)	100 (94.0 to 100)
HAI homologous strain A/H3N2	96.4 (81.7 to 99.9)	100 (96.9 to 100)	100 (96.9 to 100)	99.2 (95.4 to 100)	100 (96.9 to 100)	100 (86.8 to 100)	100 (95.1 to 100)	100 (96.9 to 100)	98.3 (94.0 to 99.8)	98.3 (91.1 to 100)
HAI homologous strain B/Yamagata-lineage	100 (87.7 to 100)	100 (96.9 to 100)	100 (96.9 to 100)	100 (97.0 to 100)	100 (96.9 to 100)	100 (86.8 to 100)	100 (95.1 to 100)	100 (96.9 to 100)	100 (96.9 to 100)	100 (94.0 to 100)
HAI homologous strain B/Victoria-lineage	100 (87.7 to 100)	100 (96.9 to 100)	100 (96.9 to 100)	100 (97.0 to 100)	100 (96.9 to 100)	100 (86.8 to 100)	98.6 (92.6 to 100)	100 (96.9 to 100)	100 (96.9 to 100)	100 (94.0 to 100)

PrimaryGeometric Mean Ratio of Hemagglutination Inhibition Antibody Titer at Day 29

The HAI Ab was measured by hemagglutinin inhibition using quality control sera (sheep, ferret and/or human sera) measurement method. The geometric mean ratio of antibody titer at post-vaccination over pre-vaccination is reported. The 95% CI was based on the Clopper-Pearson method.

Time frame:: Days 1 and 29
Reported as:: Geometric mean · ratio

Geometric Mean Ratio of Hemagglutination Inhibition Antibody Titer at Day 29
ratio	QIV mRNA LNP 1: 30 mcg	QIV mRNA LNP 1: 96 mcg	QIV mRNA LNP 1: 132 mcg	QIV mRNA LNP 1: 192 mcg	QIV mRNA LNP 2: 96 mcg	QIV mRNA LNP 2: 192 mcg	QIV mRNA LNP 3: 192 mcg	QIV-SD	RIV4	QIV-HD
HAI homologous strain A/H1N1	4.31 (2.34 to 7.92)	4.07 (3.22 to 5.14)	4.32 (3.35 to 5.57)	4.59 (3.68 to 5.74)	7.18 (5.61 to 9.20)	6.29 (3.39 to 11.7)	4.84 (3.55 to 6.59)	3.12 (2.31 to 4.21)	4.69 (3.45 to 6.39)	2.73 (1.99 to 3.76)
HAI homologous strain A/H3N2	4.53 (2.34 to 8.75)	6.34 (5.03 to 7.98)	6.85 (5.26 to 8.92)	8.93 (6.92 to 11.5)	11.4 (8.60 to 15.1)	14.0 (7.18 to 27.3)	6.68 (5.19 to 8.60)	5.44 (4.09 to 7.25)	11.0 (8.21 to 14.8)	4.59 (3.25 to 6.50)
HAI homologous strain B/Yamagata-lineage	1.60 (1.06 to 2.41)	2.12 (1.83 to 2.46)	2.15 (1.81 to 2.54)	2.34 (1.99 to 2.74)	3.08 (2.53 to 3.74)	2.29 (1.45 to 3.60)	2.14 (1.77 to 2.58)	2.82 (2.19 to 3.63)	3.08 (2.52 to 3.77)	2.30 (1.71 to 3.09)
HAI homologous strain B/Victoria-lineage	2.10 (1.32 to 3.36)	2.66 (2.20 to 3.22)	2.57 (2.13 to 3.10)	3.19 (2.63 to 3.88)	3.47 (2.86 to 4.20)	2.68 (1.85 to 3.89)	3.44 (2.73 to 4.33)	4.92 (3.78 to 6.41)	4.12 (3.17 to 5.35)	3.73 (2.64 to 5.27)

PrimaryPercentage of Participants With Seroconversion of Hemagglutination Inhibition Antibody Titer at Day 29

The seroconversion was defined as titer \<10 on Day 1 and post-injection titer \>=40 on Day 29; or defined as titer \>=10 on Day 1 and a \>=4-fold increase in titer on Day 29. The 95% CI for the single percentage was based on the Clopper-Pearson method. The percentages are rounded off to the tenth decimal place.

Time frame:: Day 29
Reported as:: Number · percentage of participants

Percentage of Participants With Seroconversion of Hemagglutination Inhibition Antibody Titer at Day 29
percentage of participants	QIV mRNA LNP 1: 30 mcg	QIV mRNA LNP 1: 96 mcg	QIV mRNA LNP 1: 132 mcg	QIV mRNA LNP 1: 192 mcg	QIV mRNA LNP 2: 96 mcg	QIV mRNA LNP 2: 192 mcg	QIV mRNA LNP 3: 192 mcg	QIV-SD	RIV4	QIV-HD
HAI homologous strain A/H1N1	50.0 (30.6 to 69.4)	51.3 (41.9 to 60.5)	56.9 (47.4 to 66.1)	63.3 (54.1 to 71.9)	71.6 (62.4 to 79.5)	65.4 (44.3 to 82.8)	63.0 (50.9 to 74.0)	35.9 (27.2 to 45.3)	51.3 (41.9 to 60.6)	38.3 (26.1 to 51.8)
HAI homologous strain A/H3N2	67.9 (47.6 to 84.1)	68.1 (58.9 to 76.3)	69.8 (60.6 to 78.0)	72.5 (63.6 to 80.3)	80.2 (71.7 to 87.0)	73.1 (52.2 to 88.4)	75.3 (63.9 to 84.7)	53.8 (44.4 to 63.1)	73.5 (64.5 to 81.2)	56.7 (43.2 to 69.4)
HAI homologous strain B/Yamagata-lineage	28.6 (13.2 to 48.7)	30.3 (22.2 to 39.3)	31.9 (23.6 to 41.2)	37.5 (28.8 to 46.8)	44.0 (34.8 to 53.5)	42.3 (23.4 to 63.1)	32.9 (22.3 to 44.9)	37.6 (28.8 to 47.0)	45.3 (36.1 to 54.8)	31.7 (20.3 to 45.0)
HAI homologous strain B/Victoria-lineage	32.1 (15.9 to 52.4)	35.3 (26.8 to 44.6)	37.1 (28.3 to 46.5)	50.8 (41.6 to 60.1)	50.0 (40.6 to 59.4)	38.5 (20.2 to 59.4)	56.2 (44.1 to 67.8)	58.1 (48.6 to 67.2)	48.7 (39.4 to 58.1)	50.0 (36.8 to 63.2)

PrimaryPercentage of Participants With Hemagglutination Inhibition Antibody Titer >=1:40 at Day 29

Time frame:: Day 29
Reported as:: Number · percentage of participants

Percentage of Participants With Hemagglutination Inhibition Antibody Titer >=1:40 at Day 29
percentage of participants	QIV mRNA LNP 1: 30 mcg	QIV mRNA LNP 1: 96 mcg	QIV mRNA LNP 1: 132 mcg	QIV mRNA LNP 1: 192 mcg	QIV mRNA LNP 2: 96 mcg	QIV mRNA LNP 2: 192 mcg	QIV mRNA LNP 3: 192 mcg	QIV-SD	RIV4	QIV-HD
HAI homologous strain A/H1N1	100 (87.7 to 100)	98.3 (94.1 to 99.8)	98.3 (93.9 to 99.8)	98.3 (94.1 to 99.8)	97.4 (92.6 to 99.5)	100 (86.8 to 100)	98.6 (92.6 to 100)	98.3 (94.0 to 99.8)	96.6 (91.5 to 99.1)	95.0 (86.1 to 99.0)
HAI homologous strain A/H3N2	92.9 (76.5 to 99.1)	92.4 (86.1 to 96.5)	96.6 (91.4 to 99.1)	95.8 (90.5 to 98.6)	98.3 (93.9 to 99.8)	96.2 (80.4 to 99.9)	97.3 (90.5 to 99.7)	94.0 (88.1 to 97.6)	96.6 (91.5 to 99.1)	91.7 (81.6 to 97.2)
HAI homologous strain B/Yamagata-lineage	96.4 (81.7 to 99.9)	99.2 (95.4 to 100)	99.1 (95.3 to 100)	99.2 (95.4 to 100)	100 (96.9 to 100)	100 (86.8 to 100)	100 (95.1 to 100)	99.1 (95.3 to 100)	100 (96.9 to 100)	100 (94.0 to 100)
HAI homologous strain B/Victoria-lineage	100 (87.7 to 100)	92.4 (86.1 to 96.5)	94.0 (88.0 to 97.5)	96.7 (91.7 to 99.1)	94.8 (89.1 to 98.1)	88.5 (69.8 to 97.6)	93.2 (84.7 to 97.7)	99.1 (95.3 to 100)	94.9 (89.2 to 98.1)	100 (94.0 to 100)

PrimaryPercentage of Participants With >=2 and >=4 Fold Increase in Hemagglutination Inhibition Antibody Titer at Day 29

Time frame:: Days 1 and 29
Reported as:: Number · percentage of participants

Percentage of Participants With >=2 and >=4 Fold Increase in Hemagglutination Inhibition Antibody Titer at Day 29
percentage of participants	QIV mRNA LNP 1: 30 mcg	QIV mRNA LNP 1: 96 mcg	QIV mRNA LNP 1: 132 mcg	QIV mRNA LNP 1: 192 mcg	QIV mRNA LNP 2: 96 mcg	QIV mRNA LNP 2: 192 mcg	QIV mRNA LNP 3: 192 mcg	QIV-SD	RIV4	QIV-HD
HAI homologous strain A/H1N1: 2-fold increase	82.1 (63.1 to 93.9)	79.0 (70.6 to 85.9)	80.2 (71.7 to 87.0)	85.8 (78.3 to 91.5)	91.4 (84.7 to 95.8)	80.8 (60.6 to 93.4)	84.9 (74.6 to 92.2)	65.8 (56.5 to 74.3)	75.2 (66.4 to 82.7)	65.0 (51.6 to 76.9)
HAI homologous strain A/H1N1: 4-fold increase	50.0 (30.6 to 69.4)	51.3 (41.9 to 60.5)	56.9 (47.4 to 66.1)	64.2 (54.9 to 72.7)	72.4 (63.3 to 80.3)	65.4 (44.3 to 82.8)	63.0 (50.9 to 74.0)	36.8 (28.0 to 46.2)	51.3 (41.9 to 60.6)	38.3 (26.1 to 51.8)
HAI homologous strain A/H3N2: 2-fold increase	82.1 (63.1 to 93.9)	89.9 (83.0 to 94.7)	89.7 (82.6 to 94.5)	93.3 (87.3 to 97.1)	94.0 (88.0 to 97.5)	92.3 (74.9 to 99.1)	94.5 (86.6 to 98.5)	77.8 (69.2 to 84.9)	90.6 (83.8 to 95.2)	83.3 (71.5 to 91.7)
HAI homologous strain A/H3N2: 4-fold increase	67.9 (47.6 to 84.1)	72.3 (63.3 to 80.1)	71.6 (62.4 to 79.5)	74.2 (65.4 to 81.7)	80.2 (71.7 to 87.0)	76.9 (56.4 to 91.0)	76.7 (65.4 to 85.8)	56.4 (46.9 to 65.6)	74.4 (65.5 to 82.0)	56.7 (43.2 to 69.4)
HAI homologous strain B/Yamagata-lineage: 2-fold increase	53.6 (33.9 to 72.5)	66.4 (57.2 to 74.8)	64.7 (55.2 to 73.3)	73.3 (64.5 to 81.0)	78.4 (69.9 to 85.5)	76.9 (56.4 to 91.0)	68.5 (56.6 to 78.9)	61.5 (52.1 to 70.4)	75.2 (66.4 to 82.7)	70.0 (56.8 to 81.2)
HAI homologous strain B/Yamagata-lineage: 4-fold increase	28.6 (13.2 to 48.7)	30.3 (22.2 to 39.3)	31.9 (23.6 to 41.2)	37.5 (28.8 to 46.8)	44.0 (34.8 to 53.5)	42.3 (23.4 to 63.1)	32.9 (22.3 to 44.9)	37.6 (28.8 to 47.0)	45.3 (36.1 to 54.8)	31.7 (20.3 to 45.0)
HAI homologous strain B/Victoria-lineage: 2-fold increase	60.7 (40.6 to 78.5)	70.6 (61.5 to 78.6)	73.3 (64.3 to 81.1)	77.5 (69.0 to 84.6)	83.6 (75.6 to 89.8)	88.5 (69.8 to 97.6)	76.7 (65.4 to 85.8)	77.8 (69.2 to 84.9)	71.8 (62.7 to 79.7)	71.7 (58.6 to 82.5)
HAI homologous strain B/Victoria-lineage: 4-fold increase	32.1 (15.9 to 52.4)	37.0 (28.3 to 46.3)	37.1 (28.3 to 46.5)	52.5 (43.2 to 61.7)	51.7 (42.3 to 61.1)	38.5 (20.2 to 59.4)	56.2 (44.1 to 67.8)	59.0 (49.5 to 68.0)	50.4 (41.0 to 59.8)	50.0 (36.8 to 63.2)

SecondaryGeometric Mean of Neutralization Test (NT) Antibody Titer at Days 1 and 29

The NT Ab was planned to be measured using seroneutralization (SN) measurement method. The 95% CI was planned to be calculated using the Clopper-Pearson method.

Time frame:: Days 1 and 29

No measurements were reported for this outcome.

SecondaryGeometric Mean Ratio of Neutralization Test Antibody Titer at Day 29

The NT Ab was planned to be measured using SN measurement method. The geometric mean ratio of antibody titer at post-vaccination over pre-vaccination was planned to be reported. The 95% CI was planned to be calculated using the Clopper-Pearson method.

Time frame:: Days 1 and 29

No measurements were reported for this outcome.

SecondaryPercentage of Participants With >=2 and >=4 Fold Increase in Neutralization Test Antibody Titer at Day 29

The NT Ab was planned to be measured using SN measurement method. The 95% CI for the single percentage was planned to be calculated using the Clopper-Pearson method.

Time frame:: Days 1 and 29

No measurements were reported for this outcome.

Adverse events

Collected over SAEs, other AEs and all-cause mortality were collected from the vaccine administration (Day 1) until 12 months after vaccine administration, approximately 366 days.. Non-serious events are listed at a 5% frequency threshold.

Adverse event summary by group
Group	Deaths	Serious	Other
QIV mRNA LNP 1: 30 mcg	0/28 (0%)	0/28 (0%)	18/28 (64.3%)
QIV mRNA LNP 1: 96 mcg	1/120 (0.8%)	4/120 (3.3%)	81/120 (67.5%)
QIV mRNA LNP 1: 132 mcg	0/118 (0%)	2/118 (1.7%)	87/118 (73.7%)
QIV mRNA LNP 1: 192 mcg	0/120 (0%)	3/120 (2.5%)	91/120 (75.8%)
QIV mRNA LNP 2: 96 mcg	0/117 (0%)	0/117 (0%)	84/117 (71.8%)
QIV mRNA LNP 2: 192 mcg	0/27 (0%)	0/27 (0%)	21/27 (77.8%)
QIV mRNA LNP 3: 192 mcg	0/75 (0%)	1/75 (1.3%)	57/75 (76%)
QIV-SD	0/119 (0%)	2/119 (1.7%)	38/119 (31.9%)
RIV4	0/119 (0%)	4/119 (3.4%)	27/119 (22.7%)
QIV-HD	1/60 (1.7%)	1/60 (1.7%)	24/60 (40%)

Most frequent serious events

Showing 10 of 20

Most frequent serious events
Event	QIV mRNA LNP 1: 30 mcg	QIV mRNA LNP 1: 96 mcg	QIV mRNA LNP 1: 132 mcg	QIV mRNA LNP 1: 192 mcg	QIV mRNA LNP 2: 96 mcg	QIV mRNA LNP 2: 192 mcg	QIV mRNA LNP 3: 192 mcg	QIV-SD	RIV4	QIV-HD
DeathGeneral disorders	0/28	1/120	0/118	0/120	0/117	0/27	0/75	0/119	0/119	1/60
Myocardial InfarctionCardiac disorders	0/28	0/120	0/118	0/120	0/117	0/27	1/75	0/119	0/119	0/60
Duodenal Ulcer PerforationGastrointestinal disorders	0/28	0/120	1/118	0/120	0/117	0/27	0/75	0/119	0/119	0/60
Hip FractureInjury, poisoning and procedural complications	0/28	0/120	1/118	0/120	0/117	0/27	0/75	1/119	0/119	0/60
DiverticulitisInfections and infestations	0/28	0/120	0/118	0/120	0/117	0/27	0/75	0/119	1/119	0/60
PneumoniaInfections and infestations	0/28	0/120	0/118	0/120	0/117	0/27	0/75	0/119	1/119	0/60
Post Procedural InfectionInfections and infestations	0/28	0/120	0/118	0/120	0/117	0/27	0/75	1/119	0/119	0/60
EncephalopathyNervous system disorders	0/28	0/120	0/118	0/120	0/117	0/27	0/75	0/119	1/119	0/60
Transient Ischaemic AttackNervous system disorders	0/28	0/120	0/118	0/120	0/117	0/27	0/75	0/119	1/119	0/60
Acute Myocardial InfarctionCardiac disorders	0/28	0/120	0/118	0/120	0/117	0/27	0/75	0/119	1/119	0/60

Most frequent other events

Most frequent other events
Event	QIV mRNA LNP 1: 30 mcg	QIV mRNA LNP 1: 96 mcg	QIV mRNA LNP 1: 132 mcg	QIV mRNA LNP 1: 192 mcg	QIV mRNA LNP 2: 96 mcg	QIV mRNA LNP 2: 192 mcg	QIV mRNA LNP 3: 192 mcg	QIV-SD	RIV4	QIV-HD
Injection Site PainGeneral disorders	11/28	69/120	76/118	79/120	74/117	17/27	49/75	23/119	18/119	12/60
FatigueGeneral disorders	11/28	43/120	52/118	59/120	42/117	15/27	35/75	13/119	10/119	12/60
MyalgiaMusculoskeletal and connective tissue disorders	11/28	46/120	55/118	60/120	49/117	14/27	34/75	10/119	8/119	9/60
HeadacheNervous system disorders	10/28	37/120	40/118	49/120	40/117	12/27	31/75	11/119	6/119	6/60
ChillsGeneral disorders	6/28	25/120	28/118	28/120	31/117	11/27	23/75	3/119	4/119	2/60
ArthralgiaMusculoskeletal and connective tissue disorders	7/28	29/120	27/118	29/120	24/117	8/27	16/75	4/119	5/119	4/60
Injection Site ErythemaGeneral disorders	0/28	8/120	10/118	16/120	11/117	7/27	10/75	1/119	3/119	3/60
Injection Site SwellingGeneral disorders	1/28	9/120	14/118	10/120	16/117	7/27	8/75	0/119	2/119	3/60
PyrexiaGeneral disorders	0/28	10/120	8/118	18/120	5/117	6/27	7/75	1/119	1/119	0/60
C-Reactive Protein IncreasedInvestigations	0/28	11/120	8/118	14/120	15/117	6/27	10/75	1/119	1/119	0/60

Baseline characteristics

All randomized participants included participants who had received the study vaccine. Participants were analyzed according to the intervention they received.

Age, Continuous
Age, Continuous(years)	QIV mRNA LNP 1: 30 mcg	QIV mRNA LNP 1: 96 mcg	QIV mRNA LNP 1: 132 mcg	QIV mRNA LNP 1: 192 mcg	QIV mRNA LNP 2: 96 mcg	QIV mRNA LNP 2: 192 mcg	QIV mRNA LNP 3: 192 mcg	QIV-SD	RIV4	QIV-HD	Total
Mean	56.8 ± 15.4	57.9 ± 16.4	55.8 ± 17.5	57.5 ± 17.2	55.6 ± 17.5	56.0 ± 18.6	56.2 ± 17.6	57.2 ± 16.5	57.0 ± 17.3	71.4 ± 4.50	57.7 ± 16.9

Sex: Female, Male
Sex: Female, Male(Participants)	QIV mRNA LNP 1: 30 mcg	QIV mRNA LNP 1: 96 mcg	QIV mRNA LNP 1: 132 mcg	QIV mRNA LNP 1: 192 mcg	QIV mRNA LNP 2: 96 mcg	QIV mRNA LNP 2: 192 mcg	QIV mRNA LNP 3: 192 mcg	QIV-SD	RIV4	QIV-HD	Total
Female	13	64	70	63	63	15	36	65	59	32	480
Male	15	57	49	57	57	12	39	54	60	28	428

Race/Ethnicity, Customized
Race/Ethnicity, Customized(Participants)	QIV mRNA LNP 1: 30 mcg	QIV mRNA LNP 1: 96 mcg	QIV mRNA LNP 1: 132 mcg	QIV mRNA LNP 1: 192 mcg	QIV mRNA LNP 2: 96 mcg	QIV mRNA LNP 2: 192 mcg	QIV mRNA LNP 3: 192 mcg	QIV-SD	RIV4	QIV-HD	Total
American Indian or Alaska Native	0	1	0	0	0	0	1	0	1	0	3
Asian	0	1	1	3	0	0	1	2	2	1	11
Black or African American	0	15	14	17	14	3	9	14	16	9	111
White	28	104	104	99	104	24	63	101	99	50	776
Mixed Origin	0	0	0	1	0	0	0	1	0	0	2
Not Reported	0	0	0	0	1	0	1	1	1	0	4
Unknown	0	0	0	0	1	0	0	0	0	0	1

Study locations

13 sites

California Research Foundation Site Number : 8400038
San Diego, California 92123-1881, United States
Indago Research and Health Center- Site Number : 8400032
Hialeah, Florida 33012, United States
Cenexel Research Centers of America- Site Number : 8400037
Hollywood, Florida 33024, United States
Brengle Family Medicine Site Number : 8400045
Indianapolis, Indiana 46260, United States
AMR Lexington- Site Number : 8400042
Lexington, Kentucky 40509, United States
Velocity Clinical Research- New Orleans Site Number : 8400053
New Orleans, Louisiana 70119, United States
The Alliance for Multispecialty Research - KCM, LLC- Site Number : 8400034
Kansas City, Missouri 64114, United States
Velocity Clinical Research Norfolk- Site Number : 8400046
Norfolk, Nebraska 68701, United States
AMR Knoxville- Site Number : 8400043
Knoxville, Tennessee 37909, United States
Clinical Trials of Texas, Inc. - PPDS- Site Number : 8400029
San Antonio, Texas 78229, United States
Cenexel JBR- Site Number : 8400051
Salt Lake City, Utah 84107, United States
Investigational Site Number : 3400001
San Pedro Sula, 21104, Honduras
Investigational Site Number : 6300002
Barrio Sabana, 00694, Puerto Rico

References and documents

Study documents

Study protocol ↗ · Mar 12, 2024
Statistical analysis plan ↗ · Jul 1, 2024

PDFs hosted by the registry, ClinicalTrials.gov.

Individual participant data

Plan to share: Yes — Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org

Timeline

Tracking since Sep 25, 2026

ElapsedEstimatedEstimated, not yet reachedSimilar studies: half by the dot; the band is the middle halfHalf of similar studies reached it by the dot; the band is the middle half, from a quarter to three quarters

Ran from Apr 2024 to primary completion in Jun 2025, 14 months.

Results were first posted in Aug 2026, 1 year 1 month after primary completion.

Of 41 industry-sponsored phase 1/2 interventional studies under Influenza, Human, half reached primary completion within 13 months of starting (the median), counting those still running; a quarter within 7 and three quarters within 16. This study's 14 months is close to that.

Counting every sponsor, half of 43 studies reached it within 12 months; a quarter within 7 and three quarters within 16.

How these figures are worked out, and which studies are left out of them.

Registered: Apr 4, 2024
First posted: Apr 12, 2024
StartActual: Apr 1, 2024
Primary completionActual: Jun 9, 2025
CompletionActual: Jun 9, 2025
Results first posted: Aug 4, 2026
Last update: Aug 4, 2026

What these dates mean

Start.: When the first participant enrolled; while estimated, when the study expects to open to recruitment.
Primary completion.: When the last participant was examined or treated to collect data for the study's main question, its primary outcome. A study that stopped early gives the date its data collection stopped.
Completion.: When the last participant's last visit took place, for every outcome, secondary ones and side effects included: the end of the study. Often later than primary completion, sometimes the same day.
Actual and Est.: Actual means the registry says the date has happened. Est. (estimated) is a date the sponsor plans or expects. It can still move, and the sponsor is expected to change it to actual once it has passed.

No changes since tracking began. The registry record was last updated on Aug 4, 2026, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗

Registry details

Key details

Study ID: NCT06361875
Lead sponsor: Sanofi Pasteur, a Sanofi Company
Responsible party: Sponsor
First posted: Apr 12, 2024
Start date: Apr 1, 2024
Primary completion: Jun 9, 2025
Completion: Jun 9, 2025
Results posted: Aug 4, 2026
Last update: Aug 4, 2026

Oversight

Data monitoring committee: No
FDA-regulated drug: Yes
FDA-regulated device: No

View the source record on ClinicalTrials.gov ↗

Not currently enrolling

This study is completed, as verified in Jul 2026. You cannot join it, but the record below documents what was studied.

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Discussion

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Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.

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A Study to Investigate the Safety and Immunogenicity of the Quadrivalent Influenza mRNA Vaccines in Adults Aged 18 Years and Above

Study summary

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Influenza, Human

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