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A Safety, Tolerability, and Immunogenicity Study of mRNA-1345 and mRNA-1365 in Participants Aged 5 Months to <24 Months | Clinical Trials | Clareo Health

ACTIVE_NOT_RECRUITINGPHASE1

A Safety, Tolerability, and Immunogenicity Study of mRNA-1345 and mRNA-1365 in Participants Aged 5 Months to <24 Months

A Phase 1, Randomized, Observer-blind, Placebo-controlled, Age De-escalation Study of the Safety, Tolerability, and Immunogenicity of mRNA-1345 and mRNA-1365 in Participants Aged 5 Months to <24 Months

NCT05743881•ModernaTX, Inc.

View on ClinicalTrials.gov

Summary

The purpose of this study is to assess the safety and immunogenicity of mRNA-1365, an mRNA vaccine targeting respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) and mRNA-1345, an mRNA vaccine targeting RSV, in participants aged 5 months to \<24 months.

Eligibility

Age

0 - 2 years

Sex

ALL

Healthy Volunteers

Inclusion Criteria

•The participant is 8 months to \<24 months (Part A), 5 months to \<8 months (Part B), or 8 months to \<12 months (Part C) of age at the time of randomization (Day 1/Baseline visit), who is in good general health, in the opinion of the Investigator, based on review of medical history and screening physical examination.
•In the Investigator's opinion, the parent(s)/ legally authorized representative (LAR)(s) understand and are willing and physically able to comply with protocol-mandated follow up, including all procedures, and provide written informed consent.
•The participant is growing normally for age in the opinion of the site clinician in the months prior to enrollment.
•The participant was born at full-term (≥37 weeks gestation) with a minimum birth weight of 2.5 kilograms (kg).
•For Part C Cohort 7: participant must have received nirsevimab ≥6 months prior to Day 1 Visit.
•For Part C Cohort 8: participant was eligible at any time since birth, according to national guidelines, to receive nirsevimab prior to Day 1 Visit but did not do so.

Exclusion Criteria

•Has a known history of symptomatic RSV (Part A: within 3 months; Part B and Part C: since birth) or hMPV infection (Part A: within 3 months; Part B: since birth) prior to administration of the first dose of investigational product (IP) or has a known close contact with anyone with laboratory-confirmed RSV (Parts A, B, and C) or hMPV infection (Parts A or B) within 14 days prior to administration of the first dose of IP.
•Is acutely ill or febrile 24 hours prior to or at the screening visit. Fever is defined as a body temperature ≥38.0°Celsius/≥100.4°Fahrenheit. Participants who meet this criterion may have visits rescheduled within the relevant study visit windows.
•Has previously been administered an investigational or approved vaccine for prevention of RSV (Parts A, B, and C) or hMPV (Parts A and B) infection or if the participant's mother received an investigational or approved vaccine for the prevention of RSV (Parts A, B, and C) or hMPV (Parts A and B) infection during pregnancy.
•Has received investigational or approved agents for prophylaxis against RSV or hMPV (for example, monoclonal antibodies) or is intending to receive these during the course of the study. For Part C (Cohort 7 only), use of nirsevimab ≥6 months before Day 1 Visit is allowed.
•Has a known hypersensitivity to a component of the vaccine or its excipients. Hypersensitivity includes, but is not limited to, anaphylaxis or immediate allergic reaction of any severity to a previous dose of an mRNA vaccine or any of its components (including polyethylene glycol or immediate allergic reaction of any severity to polysorbate).
•Has a medical condition that, according to the Investigator's judgment, may pose additional risk as a result of participation, interfere with safety assessments, or interfere with interpretation of results.

Locations (50)

Matrix Clinical Research

Los Angeles, California, United States

Los Angeles Children's Hospital

Los Angeles, California, United States

Velocity Clinical Research, Denver

Englewood, Colorado, United States

Meridian Clinical Research

Washington D.C., District of Columbia, United States

Meridian Clinical Research

Washington D.C., District of Columbia, United States

University Of Florida Health Science Center

Jacksonville, Florida, United States

Accel Research Sites - Nona Pediatric Center

Orlando, Florida, United States

Clinical Research Prime

Idaho Falls, Idaho, United States

MedPharmics - Platinum - PPDS

Lafayette, Louisiana, United States

Umass Memorial Medical Center

Worcester, Massachusetts, United States

Key Dates

Start Date

February 15, 2023

Primary Completion Date

August 31, 2026

Completion Date

September 30, 2026

Last Updated

November 24, 2025

Enrollment

186

ACTUAL participants

Conditions

Respiratory Syncytial VirusHuman Metapneumovirus

Interventions

mRNA-1345

BIOLOGICAL

mRNA-1365

BIOLOGICAL

Placebo

BIOLOGICAL

Nimenrix

DRUG

A Study on the Immune Response and Safety of Vaccine Against Respiratory Syncytial Virus Given to Chinese Adults 18 to 59 Years of Age at Increased Risk of Respiratory Syncytial Virus Disease

NCT07220109

Respiratory Syncytial Virus Infections

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RECRUITINGPHASE2

A Study Evaluating Persistence of the Immune Response of the Adjuvanted Respiratory Syncytial Virus (RSV) Vaccine and the Safety and Immune Response Following Revaccination in Adults 18 Years of Age and Above Who Received Lung or Kidney Transplant

NCT07092865

Respiratory Syncytial Virus Infections

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Data Source & Attribution

This clinical trial information is sourced from ClinicalTrials.gov, a service of the U.S. National Institutes of Health.

ClinicalTrials.gov last update: November 24, 2025Data synced to Clareo: March 29, 2026

Modifications: This data has been reformatted for display purposes. Eligibility criteria have been parsed into inclusion/exclusion sections. Location data has been geocoded to enable distance-based search. For the authoritative and most current information, please visit ClinicalTrials.gov.

Neither the United States Government nor Clareo Health make any warranties regarding the data. Check ClinicalTrials.gov frequently for updates.

View ClinicalTrials.gov Terms and Conditions

A Safety, Tolerability, and Immunogenicity Study of mRNA-1345 and mRNA-1365 in Participants Aged 5 Months to <24 Months

Inclusion Criteria

Exclusion Criteria

A Study on the Immune Response and Safety of Vaccine Against Respiratory Syncytial Virus Given to Chinese Adults 18 to 59 Years of Age at Increased Risk of Respiratory Syncytial Virus Disease

A Study Evaluating Persistence of the Immune Response of the Adjuvanted Respiratory Syncytial Virus (RSV) Vaccine and the Safety and Immune Response Following Revaccination in Adults 18 Years of Age and Above Who Received Lung or Kidney Transplant

COVID-19 Impact on RSV Emergency Presentations

Genotype and Disease Burden of RSV in Older Vietnamese Adults (RSV: Respiratory Syncytial Virus )

Antibiotic Therapy in Viral Airway Infections

Assessing Antiviral Treatments in Early Symptomatic RSV