A Study of mRNA-1345, an mRNA Vaccine Targeting Respiratory Syncytial Virus, in Children 2 to <18 Years of Age at High Risk of Respiratory Syncytial Virus

A Phase 2, Randomized, Observer-blind Study to Evaluate the Safety, Reactogenicity, and Immunogenicity of mRNA-1345, an mRNA Vaccine Targeting Respiratory Syncytial Virus, in Children 2 to <18 Years of Age at High Risk of Respiratory Syncytial Virus Disease

Part A: The purpose is to evaluate the safety, reactogenicity, and immunogenicity of mRNA-1345 in children aged 2 to <5 years (Cohort 1) and in children at high risk of respiratory syncytial virus (RSV) disease 5 to <18 years of age (Cohort 2) to inform the dose level selection for the next phase of development (Phase 3).

Part B: The purpose is to provide surveillance for RSV disease for the next RSV season (6 months after re-enrollment) and safety follow-up for Cohort 1 participants that were enrolled and dosed in Part A.

Study Overview

• Status: Completed
• Conditions: Respiratory Syncytial Virus
• Intervention / Treatment: Biological: Placebo; Biological: mRNA-1345

• Study Type: Interventional
• Enrollment (Actual): 346
• Phase: Phase 2

Contacts and Locations

Study Locations

• Panama
  • Ciudad de Panamá, Panama, 07114
    • CEVAXIN 24 de Diciembre
  • La Chorrera, Panama, 07066
    • CEVAXIN Chorrera
  • Panamá, Panama, 07093
    • CEVAXIN Avenida Mexico
• United States
  • Arizona
    • Phoenix, Arizona, United States, 85006
      • Velocity Clinical Research, Phoenix
    • Scottsdale, Arizona, United States, 85260
      • Headlands Research - Scottsdale
  • California
    • Banning, California, United States, 92220
      • Velocity Clinical Research - Banning
    • Fullerton, California, United States, 92835
      • ASCADA Research, LLC - Family Medicine
    • Long Beach, California, United States, 90815
      • ARK Clinical Research
    • Rolling Hills Estates, California, United States, 90274
      • Peninsula Research Associates (PRA)
  • Florida
    • Doral, Florida, United States, 33122
      • D&H Doral Research Center, LLC
    • Kissimmee, Florida, United States, 34741
      • Kissimmee Clinical Research
    • Largo, Florida, United States, 33777
      • Accel Clinical
    • Miami, Florida, United States, 33125
      • Med-Care Research
    • Orlando, Florida, United States, 32829
      • Accel Research Sites - Nona Pediatric Center
    • Pensacola, Florida, United States, 32501
      • SEC Clinical Research
    • Tamarac, Florida, United States, 33321
      • D&H Tamarac Research Center
  • Georgia
    • Fayetteville, Georgia, United States, 30214
      • Javara, Inc.
    • Macon, Georgia, United States, 31210
      • Velocity Clinical Research-Primary Pediatrics, Macon
    • Savannah, Georgia, United States, 31405
      • CenExel iResearch, LLC
  • Idaho
    • Idaho Falls, Idaho, United States, 83404
      • Clinical Research Prime
    • Meridian, Idaho, United States, 83642
      • Velocity Clinical Research - Boise
  • Kansas
    • El Dorado, Kansas, United States, 67042
      • Alliance for Multispeciality Research, LLC
    • Overland Park, Kansas, United States, 66210
      • Velocity Clinical Research-Kansas City
  • Louisiana
    • Lafayette, Louisiana, United States, 70508
      • Velocity Clinical Research - Lafayette
    • Metairie, Louisiana, United States, 70006
      • Velocity Clinical Research Metairie
  • Michigan
    • Southfield, Michigan, United States, 48075
      • Great Lakes Research Institute
    • Southgate, Michigan, United States, 48195-1896
      • Pediatric & Adolescent Center
  • Minnesota
    • Minneapolis, Minnesota, United States, 55402
      • Clinical Research Institute
  • Mississippi
    • Gulfport, Mississippi, United States, 39503
      • Velocity Clinical Research, Gulfport
  • New Mexico
    • Albuquerque, New Mexico, United States, 87107
      • Velocity Clinical Research- Albuquerque
  • New York
    • Binghamton, New York, United States, 13905
      • Velocity Clinical Research-Binghamton
    • Rochester, New York, United States, 14620
      • University of Rochester Medical Center (URMC) - Golisano Children's Hospital (GCH)
  • Ohio
    • South Euclid, Ohio, United States, 44121
      • Senders Pediatrics
  • Pennsylvania
    • Philadelphia, Pennsylvania, United States, 19107
      • DM Clinical Research - Philadelphia
    • Philadelphia, Pennsylvania, United States, 19104-4318
      • The Children's Hospital of Philadelphia - Pediatrics
  • Rhode Island
    • Providence, Rhode Island, United States, 02886
      • Velocity Clinical Research - Providence
  • South Carolina
    • Charleston, South Carolina, United States, 29414
      • Coastal Pediatric Research
    • Simpsonville, South Carolina, United States, 29680
      • Tribe Clinical Research
  • Texas
    • Austin, Texas, United States, 78704
      • Elligo Clinical Research Center
    • Beaumont, Texas, United States, 77701
      • REX Clinical Trials, LLC
    • Conroe, Texas, United States, 77384
      • Javara Inc (Conroe)
    • Houston, Texas, United States, 77055
      • West Houston Clinical Research Service
    • Houston, Texas, United States, 77065
      • DM Clinical Research - CyFair
    • Plano, Texas, United States, 75024
      • Village Pediatrics
    • Stephenville, Texas, United States, 76401
      • Javara Inc/Texas Health Care, PLLC d/b/a/ Privia Medical Group-North Texas
    • Victoria, Texas, United States, 77901
      • Victoria Clinical Research Group
  • Utah
    • West Jordan, Utah, United States, 84088
      • Velocity Clinical Research - Salt Lake City
  • Virginia
    • Annandale, Virginia, United States, 22003
      • PI-Coor Clinical Research, LLC
    • Richmond, Virginia, United States, 23294
      • National Clinical Research, Inc.
    • Richmond, Virginia, United States, 23226
      • Clinical Research Partners

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child
• Accepts Healthy Volunteers: Yes

Description

Key Inclusion Criteria:

Part A Cohort 1:

• 2 to <5 years of age at Day 1.
• Healthy, or with stable chronic conditions increasing the risk of RSV disease, per the clinical judgment of the Investigator.

Cohort 2:

• 5 to <18 years of age at Day 1.
• Participants with stable chronic conditions increasing the risk of RSV disease.
• Female participants of child-bearing potential may be enrolled in the study, if the participant: 1) has a negative urine pregnancy test at Screening and on the day of injection (Day 1); 2) has practiced adequate contraception or has abstained from all activities that could lead to pregnancy for 28 days prior to Day 1; 3) has agreed to continue adequate contraception through 90 days following injection; and 4) is not currently breastfeeding.

Part B: Cohort 1 Re-enrollment

Participants are eligible to be included in the study only if all of the following criteria apply:

1. Enrolled and dosed in Part A of Cohort 1; either reached EoS for Part A or were dosed and subsequently discontinued from study for various reasons. This includes participants who were lost to follow-up, if they can be re-engaged.
2. Participant's parent(s)/LAR(s) has provided written informed consent for participation in this study.

Key Exclusion Criteria (All Cohorts):

• Acutely ill or febrile (temperature ≥38.0°Celsius [100.4°Fahrenheit]) within 72 hours prior to or at the Screening Visit or Day 1.
• History of a diagnosis or condition that, in the judgment of the Investigator, may affect study assessment or compromise participant safety.
• Has received or plans to receive any licensed or authorized vaccine ≤14 days prior to the study vaccine injection (Day 1) or plans to receive a licensed or authorized vaccine within 14 days after the study vaccine injection.
• Receipt of any prior systemic immunosuppressants. Short courses (<7 days) of oral corticosteroids are allowed if completed at least 3 months prior to enrollment.
• Receipt of RSV monoclonal antibodies within 6 months prior to enrollment in the study.
• Participated in an interventional clinical study within 28 days (6 months for a study assessing a product unlicensed/unauthorized in this age group in country of residence at time of enrollment) prior to the day of enrollment or plans to do so while enrolled in this study.

Part B: Cohort 1 Re-enrollment

1. Participant is currently enrolled in another interventional clinical study.

Note: Other protocol-defined inclusion and exclusion criteria may apply.

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Part A and Part B: Cohort 1 (2 to <5 Years of Age); Part A: Participants 2 to <5 years of age will receive either a single intramuscular (IM) injection of mRNA-1345 or placebo on Day 1. Part B: Participants will have the option to be re-enrolled into a 6-month safety-follow up period.	Biological: Placebo; 0.9% sodium chloride (normal saline) injection; Biological: mRNA-1345; Sterile liquid for injection
Experimental: Part A: Cohort 2 (5 to <18 Years of Age); Participants 5 to <18 years of age will receive a single IM injection of mRNA-1345 on Day 1.	Biological: mRNA-1345; Sterile liquid for injection

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Part A: Number of Participants with Solicited Local and Systemic Adverse Reactions (ARs)	Up to 7 days postinjection
Part A: Number of Participants with Unsolicited Adverse Events (AEs)	Up to 28 days postinjection
Part A: Number of Participants With Medically Attended AEs (MAAEs)	Day 1 through end of study (EOS; Month 6)
Part A: Number of Participants With Adverse Events of Special Interest (AESIs)	Day 1 through EOS (Month 6)
Part A: Number of Participants With Serious Adverse Events (SAEs)	Day 1 through EOS (Month 6)
Part A: Number of Participants With AEs Leading to Discontinuation	Day 1 through EOS (Month 6)
Part B: Number of participants With Respiratory syncytial virus-Respiratory tract disease (RSV-RTD), Respiratory syncytial virus- Lower Respiratory tract disease (RSV-LRTD), Severe RSV-LRTD, Very Severe RSV-LRTD and RSV Hospitalization	Day 1 through EOS (Month 6)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Part A: Geometric Mean Titer (GMT) of Serum RSV Neutralizing Antibody		Day 1, Day 29, and Month 6
Part A: Geometric Mean Concentration (GMC) of Serum RSV Prefusion F Binding Antibody		Day 1, Day 29, and Month 6
Part A: Geometric Mean Fold Rise (GMFR) of Postbaseline/Baseline Neutralizing Antibody Titers and Binding Antibody Concentrations		Baseline to Day 29 and Month 6
Part A: Number of Participants With Seroresponse in RSV Neutralizing Antibody	Seroresponse is defined as a postinjection titer >4-fold-rise if Baseline is >lower limit of quantification (LLOQ) or >4 × LLOQ if Baseline titer is <LLOQ in RSV neutralizing antibody titers at Day 29 and Month 6.	Baseline to Day 29 and Month 6
Part B: Number of Participants With AESIs		Day 1 through EOS (Month 6)
Part B: Number of Participants With SAEs		Day 1 through EOS (Month 6)

Collaborators and Investigators

• Sponsor: ModernaTX, Inc.

Study record dates

Study Major Dates

• Study Start (Actual): October 24, 2023
• Primary Completion (Actual): June 27, 2025
• Study Completion (Actual): June 27, 2025

Study Registration Dates

• First Submitted: October 18, 2023
• First Submitted That Met QC Criteria: October 18, 2023
• First Posted (Actual): October 24, 2023

Study Record Updates

• Last Update Posted (Actual): July 10, 2025
• Last Update Submitted That Met QC Criteria: July 8, 2025
• Last Verified: July 1, 2025

More Information

Terms related to this study

• Keywords: Pediatric; Moderna; Messenger RNA; Viral Diseases; mRNA-1345; RSV vaccine
• Additional Relevant MeSH Terms: Infections; Virus Diseases
• Other Study ID Numbers: mRNA-1345-P202; 2024-000502-15 (EudraCT Number)

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No