Safety and Immunogenicity of an mRNA Respiratory Syncytial Virus Vaccine, mRNA-1345, in Healthy and High-Risk Pediatric Populations Aged 2 to 17 Years
Abstract
Background: Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infections (LRTIs) in infants and children. No active RSV vaccine is currently available for children. mRNA-1345 is an investigational mRNA-based RSV vaccine encoding the prefusion F (preF) glycoprotein.
Method: This phase 2, randomized, observer-blind study evaluated a single dose of mRNA-1345 in children aged 2 to <18 years who were healthy (2 to <5 years only) or had stable chronic conditions associated with increased RSV risk. Children aged 2 to <5 years received 7.5-, 15-, or 30-µg mRNA-1345 or placebo, whereas children aged 5 to <18 years received 15-, 30-, or 50-µg mRNA-1345. The primary objective was safety and reactogenicity (Part A); the secondary objective was immunogenicity. RSV surveillance was conducted from 6 to 12 months post-immunization in a subset of re-enrolled participants from the 2- to <5-year-old cohort (Part B).
Results: Overall, 346 participants received study vaccination. Across dose levels and age cohorts, mRNA-1345 was well tolerated, with no vaccine-related serious adverse events or discontinuations. mRNA-1345 elicited robust increases in RSV-A and RSV-B neutralizing antibody titers and preF-biased responses by day 29. During Part B surveillance, RSV infections were infrequent, with no severe/hospitalized RSV-LRTIs.
Conclusions: mRNA-1345 demonstrated a favorable safety profile and was immunogenic in a predominantly RSV-seropositive pediatric population. These results support potential further clinical development of this vaccine in children aged >2 years at increased RSV risk, with further evaluation required to characterize the benefit-risk profile in RSV-naïve children.
Clinical Trials Registration: NCT06097299
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BibTeX
@article{moore2026safety,
title = {{Safety and Immunogenicity of an mRNA Respiratory Syncytial Virus Vaccine, mRNA-1345, in Healthy and High-Risk Pediatric Populations Aged 2 to 17 Years}},
author = {Jennifer Moore and Hui Qian and Sonia K Stoszek and Richard Bennett and Shelly Senders and Scott Striplin and Jennifer L Nayak and Matthew D Snape},
journal = {Open forum infectious diseases},
year = {2026},
month = oct,
doi = {10.1093/ofid/ofag679},
url = {https://europepmc.org/article/PMC/PMC13728700},
note = {CC BY},
}
RIS
TY - JOUR
TI - Safety and Immunogenicity of an mRNA Respiratory Syncytial Virus Vaccine, mRNA-1345, in Healthy and High-Risk Pediatric Populations Aged 2 to 17 Years
AU - Jennifer Moore
AU - Hui Qian
AU - Sonia K Stoszek
AU - Richard Bennett
AU - Shelly Senders
AU - Scott Striplin
AU - Jennifer L Nayak
AU - Matthew D Snape
PY - 2026
DA - 2026/10/17
JO - Open forum infectious diseases
DO - 10.1093/ofid/ofag679
UR - https://europepmc.org/article/PMC/PMC13728700
AB - Background: Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infections (LRTIs) in infants and children. No active RSV vaccine is currently available for children. mRNA-1345 is an investigational mRNA-based RSV vaccine encoding the prefusion F (preF) glycoprotein. Method: This phase 2, randomized, observer-blind study evaluated a single dose of mRNA-1345 in children aged 2 to <18 years who were healthy (2 to <5 years only) or had stable chronic conditions associated with increased RSV risk. Children aged 2 to <5 years received 7.5-, 15-, or 30-µg mRNA-1345 or placebo, whereas children aged 5 to <18 years received 15-, 30-, or 50-µg mRNA-1345. The primary objective was safety and reactogenicity (Part A); the secondary objective was immunogenicity. RSV surveillance was conducted from 6 to 12 months post-immunization in a subset of re-enrolled participants from the 2- to <5-year-old cohort (Part B). Results: Overall, 346 participants received study vaccination. Across dose levels and age cohorts, mRNA-1345 was well tolerated, with no vaccine-related serious adverse events or discontinuations. mRNA-1345 elicited robust increases in RSV-A and RSV-B neutralizing antibody titers and preF-biased responses by day 29. During Part B surveillance, RSV infections were infrequent, with no severe/hospitalized RSV-LRTIs. Conclusions: mRNA-1345 demonstrated a favorable safety profile and was immunogenic in a predominantly RSV-seropositive pediatric population. These results support potential further clinical development of this vaccine in children aged >2 years at increased RSV risk, with further evaluation required to characterize the benefit-risk profile in RSV-naïve children. Clinical Trials Registration: NCT06097299
SN - 2328-8957
ER -