NCT06097299

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

Completed Phase 2 Last updated 10 July 2025

What this trial tests

Phase 2 trial testing mRNA-1345 in Respiratory Syncytial Virus in 346 participants. Completed in 27 June 2025.

Timeline

24 October 2023

Primary endpoint
27 June 2025

27 June 2025

Quick facts

Lead sponsor	ModernaTX, Inc.
Phase	Phase 2
Status	Completed
Study type	INTERVENTIONAL
Allocation	randomized
Design	parallel
Masking	quadruple
Primary purpose	prevention
Enrollment	346
Start date	24 October 2023
Primary completion	27 June 2025
Estimated completion	27 June 2025
Sites	50 locations across Panama, United States

Drugs / interventions tested

• mRNA-1345 — full drug profile →
• Placebo

Conditions studied

• Respiratory Syncytial Virus — all drugs for Respiratory Syncytial Virus →

Sponsor

ModernaTX, Inc. — full company profile →

Who can join

Adults 2 to 17, any sex, with Respiratory Syncytial Virus. Patients with the condition only — healthy volunteers not accepted.

Sponsor's own description

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.

Publications & conference data

8 peer-reviewed publications reference this trial (live from Europe PMC):

1. Progress and prospects of mRNA-based drugs in pre-clinical and clinical applications.
   Shi Y, Shi M, Wang Y, You J. · · 2024 · cited 67× · PMID 39543114 · DOI 10.1038/s41392-024-02002-z
2. The respiratory syncytial virus vaccine and monoclonal antibody landscape: the road to global access.
   Terstappen J, Hak SF, Bhan A, Bogaert D, et al · · 2024 · cited 54× · PMID 39326422 · DOI 10.1016/s1473-3099(24)00455-9
3. Global progress in clinical research on human respiratory syncytial virus vaccines.
   Peng R, Chen C, Chen Q, Zhang Y, et al · · 2024 · cited 8× · PMID 39286350 · DOI 10.3389/fmicb.2024.1457703
4. Recent advances in the prevention of respiratory syncytial virus in pediatrics.
   Lipp MA, Empey KM. · · 2024 · cited 7× · PMID 38299987 · DOI 10.1097/mop.0000000000001336
5. A Systematic Review of Clinical Trials Using mRNA Vaccines for Infectious Diseases other than COVID-19.
   Sofroniou A, Ridley A. · · 2025 · cited 2× · PMID 40756606 · DOI 10.3389/bjbs.2025.14557
6. Safety and immunogenicity of an mRNA-based RSV vaccine in seropositive children aged 12-59 months.
   Schnyder Ghamloush S, Fanning S, Essink B, Eder F, et al · · 2025 · cited 1× · PMID 40953212 · DOI 10.1080/21645515.2025.2557676
7. Immunology of RNA-based vaccines: The critical interplay between inflammation and expression.
   Tregoning JS, Wang Z, Sridhar S, Shattock RJ, et al · · 2025 · cited 1× · PMID 40926412 · DOI 10.1016/j.ymthe.2025.09.011
8. Preventing RSV Infection in Children: Current Passive Immunizations and Vaccine Development.
   Babawale PI, Martínez-Espinoza I, Mitchell AM, Guerrero-Plata A. · · 2025 · cited 1× · PMID 40005481 · DOI 10.3390/pathogens14020104