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H3 mRNA/ LNP Vaccine

Phase 1

Influenza Immunization | Monoclonal antibody | Infectious Disease |Sanofi|Last Updated: Sep 12, 2025

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindACTIVE_CONTROLLED
Total Trials1
Total Enrollment159

FDA Designations

No designations recorded

Clinical trial landscape

H3 mRNA/ LNP Vaccine · 1 trial · 1 indication

Phase 1 1
NCT05829356Substudy 01 - Safety and Immunogenicity of One Monovalent Modified mRNA Vaccine Encoding Influenza Hemagglutinin With LNP, in Adult Participants Aged 18 to 49 Years and 60 Years and AboveInfluenza Immunization
COMPLETED159 Analytics
PHASE1COMPLETED
Substudy 01 - Safety and Immunogenicity of One Monovalent Modified mRNA Vaccine Encoding Influenza Hemagglutinin With LNP, in Adult Participants Aged 18 to 49 Years and 60 Years and Above
Influenza ImmunizationUnlock trial analytics

Study Endpoints

Primary Endpoints

Number of participants with immediate adverse events (AEs)
Within 30 minutes after vaccination

Unsolicited systemic AEs that occur within 30 minutes after vaccination

Number of participants with solicited injection site or systemic reaction
Within 7 days from vaccination

Number of participants reporting Adverse reactions pre-listed in the protocol and case report form (CRF) * Injection site reactions: pain, redness, swelling * Systemic reactions: fever, headache, malaise, myalgia, arthralgia, chills

Number of participants with unsolicited adverse events
Up to 28 days after injection

Unsolicited (spontaneously reported) adverse events not fulfilling criteria for solicited reactions

Presence of out-of-range biological test results
At Day 3, Day 9 or Day 29

Number of participants with biological safety assessment values out of normal range (as per the laboratory performing the test)

Presence of serious adverse events (SAEs)
Throughout Study (up to approximately Month 6)

Number of participants experiencing SAEs

Presence of adverse events of special interest (AESIs)
Throughout Study (up to approximately Month 6)

Number of participants experiencing AESIs

Hemagglutination inhibition (HAI) antibody (Ab) response to homologous strain
Day 29

Antibody are expressed as geometric mean titers (GMTs) at baseline and post-baseline

HAI titers at D01
Day 1

Antibody titers are expressed as GMTs at baseline and post-baseline

HAI titers at D29
Day 29

Antibody titers are expressed as GMTs at baseline and post-baseline

Individual HAI Ab titer ratio
Day 1 through Day 29

Individual HAI Ab titer ratio will be calculated as: D29/D01

Number of Participants with Vaccine Response or Seroconversion
Day 1 through Day 29

Seroconversion (HAI Ab titer \< 10 \[1/dil\] at D01 and post-injection titer ≥ 40 \[1/dil\] at D29, or titer ≥ 10 \[1/dil\] at D01 and a ≥ 4-fold increase in titer \[1/dil\] at D29)

2-fold and 4-fold rise in HAI titers from D01 to D29
Day 1 to Day 29

Expressed as percentage post-baseline

Percentage of participants with detectable antibody HAI titers greater than or equal to (≥) 40 [1/dil]
Day 29
Geometric Mean Titers (GMTs) of neutralizing antibody (nAb) titers at Day 1
Day 1

Nab titers at Day 1

Geometric Mean Titers (GMTs) of neutralizing antibody (nAb) titers at Day 29
Day 29

Nab titers at Day 29

Individual nab titer ratio
Day 1 through Day 29

Individual nab titer ratio will be calculated as: D29/D01

2-fold and 4-fold increase in neutralizing Ab titers from D01 to D29
Day 1 to Day 29

Expressed as percentage post-baseline

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Study Design & Arms

AllocationRANDOMIZED
MaskingDOUBLE
ModelPARALLEL
PurposePREVENTION

Treatment Arms

ArmTypeDescription
Group 1: H3 mRNA /LNP dose 1EXPERIMENTALParticipants will receive one intramuscular (IM) dose of H3 mRNA/LNP at Day 01
Group 2: H3 mRNA /LNP dose 2EXPERIMENTALParticipants will receive one IM dose of H3 mRNA/LNP at Day 01
Group 3: H3 mRNA /LNP dose 3EXPERIMENTALParticipants will receive one IM dose of H3 mRNA/LNP at Day 01
Group 4: H3 mRNA /LNP dose 4EXPERIMENTALParticipants will receive one IM dose of H3 mRNA/LNP at Day 01
Group 5: H3 mRNA /LNP dose 5EXPERIMENTALParticipants will receive one IM dose of H3 mRNA/LNP at Day 01
Group 6 (Control Group): RIV4 doseACTIVE_COMPARATORParticipants will receive one IM dose of RIV4 at Day 01

Interventions

NameTypeDescription
H3 mRNA / LNP VaccineBIOLOGICALPharmaceutical Form: Suspension for injection Route of Administration: Intra-Muscular
Quadrivalent recombinant influenza Vaccine (RIV4)BIOLOGICALPharmaceutical Form: Solution for injection in a pre-filled syringe Route of Administration: Intra-Muscular
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Eligibility Criteria

Age Range18 Years to N/A
SexALL
Healthy VolunteersYes
Study Sites8

Inclusion Criteria: * Aged 18 years and above on the day of inclusion \*Aged 18 years to 49 years or 60 years and above on the day of inclusion (substudy 01) * A female participant is eligible to participate if she is not pregnant or breastfeeding and one of the following conditions applies: ...

Countries:AustraliaUnited Kingdom
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Frequently asked questions about H3 mRNA/ LNP Vaccine

What is H3 mRNA/LNP Vaccine used for?

H3 mRNA/LNP Vaccine is an investigational messenger RNA vaccine being developed for influenza immunization. It encodes influenza hemagglutinin and is formulated with lipid nanoparticles. The vaccine is intended to generate an immune response against influenza, though it remains in clinical development and is not yet approved.

Who makes H3 mRNA/LNP Vaccine?

H3 mRNA/LNP Vaccine is being developed by Sanofi, a global biopharmaceutical company traded on the stock exchange under the ticker symbol SNY. Sanofi is conducting clinical trials to evaluate the safety and immunogenicity of this investigational vaccine for influenza immunization.

What phase is H3 mRNA/LNP Vaccine in?

H3 mRNA/LNP Vaccine is in Phase 1 clinical development. It is an investigational vaccine and has not been approved by regulatory authorities. The Phase 1 trial has been completed, and the vaccine remains under evaluation for safety and immunogenicity in adult participants.

What clinical trials is H3 mRNA/LNP Vaccine in?

H3 mRNA/LNP Vaccine has one completed Phase 1 trial registered as NCT05829356. This study evaluated the safety and immunogenicity of a monovalent modified mRNA vaccine encoding influenza hemagglutinin with lipid nanoparticles in adults aged 18 to 49 years and 60 years and above. The trial enrolled 159 participants in Australia and the United Kingdom.

Is H3 mRNA/LNP Vaccine the same as a traditional flu vaccine?

H3 mRNA/LNP Vaccine is not the same as a traditional flu vaccine. It is an mRNA-based vaccine that encodes influenza hemagglutinin, delivered via lipid nanoparticles. This approach differs from conventional inactivated or live-attenuated influenza vaccines. The vaccine is still investigational and in Phase 1 clinical development.