A Study to Investigate the Immunogenicity and Safety of mRNA-1345 Vaccine Targeting Respiratory Syncytial Virus (RSV) in High-risk Adults

August 5, 2025 updated by: ModernaTX, Inc.

A Phase 3 Study to Evaluate the Immunogenicity and Safety of mRNA-1345, an mRNA Vaccine Targeting Respiratory Syncytial Virus, in High-Risk Adults

The study is divided into 2 parts (Part A and Part B). Part A of the study will evaluate the safety and immune response to mRNA-1345 in high-risk adults aged ≥18 to <60 years.

Part B of the study will evaluate the safety and immune response to mRNA-1345 in adults who received solid organ transplant (SOT).

Study Overview

Status

Active, not recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Actual)

1153

Phase

  • Phase 3

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Canada
      • Quebec, Canada, G1V 4T3
        • Diex Recherche - Québec - PPDS
    • Alberta
      • Edmonton, Alberta, Canada, T6G 2B7
        • University of Alberta
    • British Columbia
      • Kelowna, British Columbia, Canada, V1Y 1Z9
        • OCT Research ULC (dba Okanagan Clinical Trials)
    • Nova Scotia
      • Halifax, Nova Scotia, Canada, L7 8XZ
        • Canadian Center for Vaccinology
      • Truro, Nova Scotia, Canada, B2N 1L2
        • Colchester Research Group
    • Quebec
      • Sherbrooke, Quebec, Canada, J1L 0H8
        • Diex Recherche - Sherbrooke - PPDS
  • Puerto Rico
      • San Juan, Puerto Rico, 00918
        • Caribbean Medical Research Center
  • United Kingdom
      • Aberdeen, United Kingdom, AB25 2ZD
        • Aberdeen Royal Infirmary - PPDS
      • London, United Kingdom, NW3 2QG
        • The Royal Free Hospital
    • Devon
      • Exeter, Devon, United Kingdom, EX2 5DW
        • Royal Devon and Exeter Hospital
    • Lancashire
      • Blackpool, Lancashire, United Kingdom, FY3 7EN
        • Fylde Coast Clinical Research
    • Merseyside
      • Liverpool, Merseyside, United Kingdom, L7 8XZ
        • Liverpool School of Tropical Medicine
  • United States
    • Arizona
      • Glendale, Arizona, United States, 85308-5093
        • Lenzmeier Family Medicine - CCT - PPDS
      • Phoenix, Arizona, United States, 85044-6097
        • Foothills Research Center - CCT - PPDS
      • Tempe, Arizona, United States, 85283-1528
        • Fiel Family & Sports Medicine - PC - CCT - PPDS
    • Arkansas
      • Little Rock, Arkansas, United States, 72205
        • Baptist Health Center For Clinical Research
    • California
      • Los Angeles, California, United States, 90095-3075
        • David Geffen School of Medicine at UCLA
      • San Diego, California, United States, 92103-2209
        • Artemis Institute For Clinical Research LLC - San Diego - Headlands - PPDS
    • Colorado
      • Lakewood, Colorado, United States, 80228
        • Critical Care, Pulmonary and Sleep Associates / CCT Research
    • Connecticut
      • New Haven, Connecticut, United States, 06510-2483
        • Yale University School of Medicine
    • Florida
      • Boca Raton, Florida, United States, 33434
        • Excel Medical Clinical Trials DBA Flourish
      • Hialeah, Florida, United States, 33012-4170
        • Indago Research and Health Center
      • Hollywood, Florida, United States, 33024-2709
        • CenExel RCA - Hollywood
    • Georgia
      • Stockbridge, Georgia, United States, 30281-9054
        • Clinical Research Atlanta - Headlands - PPDS
    • Idaho
      • Idaho Falls, Idaho, United States, 83404-7573
        • Snake River Research, PLLC
    • Illinois
      • Chicago, Illinois, United States, 60637-1443
        • University of Chicago
      • Peoria, Illinois, United States, 61614-4885
        • AES - DRS - Optimal Research Illinois - Peoria
    • Louisiana
      • Covington, Louisiana, United States, 70433
        • Benchmark Research - Covington - HyperCore - PPDS
    • Maryland
      • Rockville, Maryland, United States, 20854-2960
        • Velocity Clinical Research (Rockville - Maryland) - PPDS
    • Michigan
      • Detroit, Michigan, United States, 48202-2608
        • Henry Ford Hospital
      • Southfield, Michigan, United States, 48076-5412
        • DM Clinical Research - Southfield - ERN - PPDS
    • Nebraska
      • Lincoln, Nebraska, United States, 68510
        • Velocity Clinical Research (Lincoln - Nebraska) - PPDS
    • New York
      • Bronx, New York, United States, 10467-2401
        • Montefiore Medical Center - BRANY - PPDS
      • Rochester, New York, United States, 14621-3011
        • University of Rochester - Rochester General Hospital - PPDS
    • North Carolina
      • Durham, North Carolina, United States, 27710
        • Duke University Medical Center
    • Pennsylvania
      • Philadelphia, Pennsylvania, United States, 19107-1530
        • DM Clinical Research - Philadelphia - ERN - PPDS
    • Texas
      • Fort Worth, Texas, United States, 76135-5283
        • Benchmark Research - Fort Worth - HyperCore - PPDS
      • Houston, Texas, United States, 77065-5685
        • DM Clinical Research - Cyfair Clinical Research Center
      • San Angelo, Texas, United States, 76904-7610
        • Benchmark Research - San Angelo - HyperCore - PPDS
      • Tomball, Texas, United States, 77375-6543
        • DM Clinical Research - ERN - PPDS
    • Utah
      • Springville, Utah, United States, 84663
        • Springville Dermatology - CCT - PPDS
    • Virginia
      • Hampton, Virginia, United States, 23666-6262
        • Velocity Clinical Research - Hampton - PPDS
      • Suffolk, Virginia, United States, 23435-3763
        • Centricity Research Suffolk Family Medicine
      • Suffolk, Virginia, United States, 23435
        • Velocity Clinical Research - Family Practice - Suffolk - PPDS

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Key Inclusion Criteria:

Part A:

  • Adults ≥18 to <60 years of age at the time of consent who are primarily responsible for self-care and activities of daily living.

  • Documented confirmation by a physician of the diagnosis of at least one of the following conditions:

    1. Coronary artery disease and/or congestive heart failure.
    2. Chronic lung disease (for example, including but not limited to chronic obstructive pulmonary disease or persistent asthma).
    3. Stable type 1 or type 2 diabetes mellitus controlled with at least 1 medication started 90 days or more prior to Day 1.

Part B:

  • Adults ≥18 years of age at the time of consent who are primarily responsible for self-care and activities of daily living.
  • Recipient of an SOT (kidney, liver, or lung transplant) ≥180 days prior to day of consent and receiving chronic immunosuppressive therapy for the prevention of allograft rejection.

Parts A and B:

- Able to comply with study requirements.

Key Exclusion Criteria:

Part A:

  • Participation in an another clinical research trial where the participant has received an investigational product 180 days prior to Day 1. Participation in an RSV trial at any time prior to Day 1 is exclusionary.
  • History of a diagnosis or condition, that, in the judgment of the Investigator, is clinically unstable or may affect participant safety, assessment of safety endpoints, assessment of immune response, or adherence to study procedures.
  • Reported history of anaphylaxis or severe hypersensitivity reaction after receipt of the mRNA-1345 injection or any components of the mRNA-1345 injection.
  • Chronic administration (defined as more than 14 continuous days) of immunosuppressants or other immune-modifying drugs within 180 days prior to Day 1.
  • History of myocarditis, pericarditis, or myopericarditis.

Part B:

  • Previous treatment with alemtuzumab or rituximab within 2 years prior to Day 1.
  • Previous treatment with plasmapheresis within 30 days prior to Day 1.
  • A history of complications of immunosuppression.
  • A history of biopsy proven or clinically diagnosed rejection within 90 days prior to Day 1 or suspected active chronic rejection according to the Investigator's judgment.

Note: Other protocol-defined inclusion/exclusion criteria apply

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Part A: mRNA-1345 Dose 1
Single injection of mRNA-1345 administered intramuscularly (IM) on Day 1.
Biological: mRNA-1345
Sterile liquid for injection
Experimental: Part A: mRNA-1345 Dose 2
Single injection of mRNA-1345 administered IM on Day 1.
Biological: mRNA-1345
Sterile liquid for injection
Experimental: Part B: mRNA-1345 Dose 2
Two injections of mRNA-1345 administered IM on Day 1 and Day 57.
Biological: mRNA-1345
Sterile liquid for injection

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Number of Participants with Solicited Local and Systemic Adverse Reactions (ARs)
Time Frame: Day 1 through Day 7 (7 days post injection) for Part A and Day 1 through Day 64 (7 days post second injection) for Part B
Day 1 through Day 7 (7 days post injection) for Part A and Day 1 through Day 64 (7 days post second injection) for Part B
Number of Participants with Unsolicited Adverse Events (AEs)
Time Frame: Day 1 through Day 28 (28 days post injection) for Part A and Day 1 through Day 84 (28 days post second injection) for Part B
Day 1 through Day 28 (28 days post injection) for Part A and Day 1 through Day 84 (28 days post second injection) for Part B
Number of Participants With Medically Attended AEs (MAAEs)
Time Frame: Day 1 through Month 6 (for Part A) and Day 1 through Month 9 (for Part B)
Day 1 through Month 6 (for Part A) and Day 1 through Month 9 (for Part B)
Number of Participants With Serious Adverse Events (SAEs), Adverse Events of Special Interest (AESIs), and AEs Leading to Discontinuation
Time Frame: Day 1 through End of Study (Day 730)
Day 1 through End of Study (Day 730)
Part A: Geometric Mean Titer (GMT) of Serum Respiratory Syncytial Virus Subtype A (RSV-A) and Respiratory Syncytial Virus Subtype B (RSV-B) Neutralizing Antibodies (Abs) at Day 29
Time Frame: Day 29
Day 29
Part B: GMT of Serum RSV-A and RSV-B Neutralizing Abs at Day 85
Time Frame: Day 85
Day 85

Secondary Outcome Measures

Outcome Measure
Time Frame
Part A: Seroresponse Rate (SRR) of RSV-A and RSV-B Neutralizing Abs on Day 29
Time Frame: Day 29
Day 29
Part A: GMT of Serum RSV-A and RSV-B Neutralizing Abs at Day 29
Time Frame: Day 29
Day 29
Part B: GMT of Serum RSV-A and RSV-B Neutralizing Abs at Day 29
Time Frame: Day 29
Day 29
Part B: SRR of Serum RSV-A and RSV-B Neutralizing Abs on Day 29
Time Frame: Day 29
Day 29
Part B: SRR of Serum RSV-A and RSV-B Neutralizing Abs on Day 85
Time Frame: Day 85
Day 85
Part A: Geometric Mean Concentration (GMC) of Serum RSV Prefusion Conformation of the F Protein (Pre-F) Binding Abs
Time Frame: Up to End of Study (Day 730)
Up to End of Study (Day 730)
Part A: Geometric Mean Fold-Rise (GMFR) of Serum RSV Pre-F Binding Abs
Time Frame: Up to End of Study (Day 730)
Up to End of Study (Day 730)
Part A: SRR of Serum RSV Pre-F Binding Abs at Postbaseline/Baseline Levels
Time Frame: Baseline up to Day 730
Baseline up to Day 730
Part A: Number of Participants with ≥2-Fold Increase in RSV Pre-F Binding Abs
Time Frame: Up to End of Study (Day 730)
Up to End of Study (Day 730)
Part A: GMT of Postinjection/Baseline Titers to RSV-A and RSV-B Neutralizing Abs
Time Frame: Baseline up to Day 730
Baseline up to Day 730
Part A: GMFR of Postinjection/Baseline Titers to RSV-A and RSV-B Neutralizing Abs
Time Frame: Baseline up to Day 730
Baseline up to Day 730
Part A: SRR of Serum RSV-A and RSV-B Neutralizing Abs
Time Frame: Up to End of Study (Day 730)
Up to End of Study (Day 730)
Part A: Number of Participants with ≥2-Fold Increase in RSV-A and RSV-B Neutralizing Abs Titers
Time Frame: Up to End of Study (Day 730)
Up to End of Study (Day 730)
Part B: GMFR of Serum RSV-A and RSV-B Neutralizing Abs
Time Frame: Up to End of Study (Day 730)
Up to End of Study (Day 730)
Part B: SRR of Serum RSV-A and RSV-B Neutralizing Abs at Postbaseline/Baseline Levels
Time Frame: Baseline up to Day 730
Baseline up to Day 730
Part B: Number of Participants with ≥2-Fold Increase in RSV-A and RSV-B Neutralizing Abs
Time Frame: Up to End of Study (Day 730)
Up to End of Study (Day 730)
Part B: GMC of Serum RSV Pre-F Binding Abs
Time Frame: Up to End of Study (Day 730)
Up to End of Study (Day 730)
Part B: GMFR of Serum RSV Pre-F Binding Abs
Time Frame: Up to End of Study (Day 730)
Up to End of Study (Day 730)
Part B: SRR of Serum RSV Pre-F Binding Abs at Postbaseline/Baseline Levels
Time Frame: Baseline up to End of Study (Day 730)
Baseline up to End of Study (Day 730)
Part B: Number of Participants with ≥2-Fold Increase in RSV Pre-F Binding Abs
Time Frame: Up to End of Study (Day 730)
Up to End of Study (Day 730)
Part B: GMT of Serum RSV-A and RSV-B Neutralizing Abs
Time Frame: Up to End of Study (Day 730)
Up to End of Study (Day 730)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

ModernaTX, Inc.

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

October 6, 2023

Primary Completion (Estimated)

July 30, 2026

Study Completion (Estimated)

July 30, 2026

Study Registration Dates

First Submitted

September 27, 2023

First Submitted That Met QC Criteria

September 27, 2023

First Posted (Actual)

October 4, 2023

Study Record Updates

Last Update Posted (Actual)

August 8, 2025

Last Update Submitted That Met QC Criteria

August 5, 2025

Last Verified

August 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • mRNA-1345-P303

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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