A Phase 2 interventional study of mRNA-1345 and Placebo in Respiratory Syncytial Virus, sponsored by ModernaTX, Inc.. Completed at 56 sites in 8 countries. Open to participants aged 0 Years to 40 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-06-10.
Sponsored by ModernaTX, Inc. · Phase 2, Interventional, and Prevention
The purpose of the study is to evaluate the reactogenicity, safety, and immunogenicity of an investigational respiratory syncytial virus (RSV) vaccine, mRNA-1345, in pregnant women, and safety and immunogenicity in infants born to vaccinated mothers.
914 studies on the registry are indexed under Virus Diseases; 110 are open to participants now.
This study's enrollment of 360 is above the median of 102 across 604 interventional studies indexed under Virus Diseases.
Browse Virus Diseases studies →ModernaTX, Inc. is the lead sponsor of 112 studies on the registry; 14 are open to participants now.
Of its 60 completed or terminated interventional studies of FDA-regulated products, 32 (53%) have results posted.
Counted across the registry records on this site, refreshed daily.
Key Inclusion Criteria:
Maternal Participants
Specific inclusion criteria for Japanese pregnant women:
Infant Participants
Key Exclusion Criteria:
Maternal Participants
Infant Participants
Other inclusion and exclusion criteria may apply.
Participants will be vaccinated in the period from 28 weeks to 36 weeks of gestation with a single intramuscular (IM) injection of mRNA-1345 Dose A.
Biological: mRNA-1345
Participants will be vaccinated in the period from 28 weeks to 36 weeks of gestation with a single IM injection of mRNA-1345 Dose B.
Biological: mRNA-1345
Participants will be vaccinated in the period from 28 weeks to 36 weeks of gestation with a single IM injection of mRNA-1345 Dose C.
Biological: mRNA-1345
Participants will receive single IM injection of mRNA-1345 vaccine matching placebo in the period from 28 weeks to 36 weeks of gestation.
Biological: Placebo
Sterile liquid for injection
0.9% sodium chloride (normal saline) injection
Number of Maternal Participants with Solicited Local and Systemic Adverse Reactions (ARs)
Time frame: Up to Day 7 (7 days post vaccination)
Number of Maternal Participants with Unsolicited Adverse Events (AEs)
Time frame: Up to Day 28 (28 days post vaccination)
Number of Maternal Participants with Medically-Attended AEs (MAAEs)
Time frame: Day 1 to Month 6 (6 months postdelivery)
Number of Maternal Participants with Adverse Events of Special Interest (AESIs)
Time frame: Day 1 to Month 12 (12 months postdelivery)
Number of Maternal Participants with Serious Adverse Events (SAEs)
Time frame: Day 1 to Month 12 (12 months postdelivery)
Number of Maternal Participants with AEs Leading to Discontinuation
Time frame: Day 1 to Month 12 (12 months postdelivery)
Number of Maternal Participants With Pregnancy Outcomes
Pregnancy outcomes will include stillbirth, live birth, vaginal delivery, and cesarean section delivery.
Time frame: Day 1 to Month 12 (12 months postdelivery)
Number of Infant Participants with MAAEs
Time frame: Day 1 (birth) to Month 12
Number of Infant Participants with AESIs
Time frame: Day 1 (birth) to Month 12
Number of Infant Participants with SAEs
Time frame: Day 1 (birth) to Month 12
Number of Infant Participants With Birth Outcomes
Birth outcomes will include gestational age and anthropometric measurements.
Time frame: Day 1 (birth) to Month 12
Geometric Mean Titer (GMT) of Serum RSV-A and RSV-B Neutralizing Antibodies in Maternal Participants
Time frame: Day 1, Day 29, delivery, and Month 6 (6 months postdelivery)
Geometric Mean Concentration (GMC) of Serum RSV-F Binding Antibodies in Maternal Participants
Time frame: Day 1, Day 29, delivery, and Month 6 (6 months postdelivery)
Geometric Mean Fold-Rise (GMFR) of Postbaseline/Baseline Neutralizing Antibody Titers and Binding Antibody Concentrations in Maternal Participants
Time frame: Day 29, delivery, and Month 6 (6 months postdelivery)
Percentage of Maternal Participants With ≥4-fold Increase From Baseline in Neutralizing Antibody Titers and Binding Antibody Concentrations
Time frame: Baseline up to Month 6 (6 months postdelivery)
GMT of Serum RSV-A and RSV-B Neutralizing Antibodies in Infant Participants
Time frame: Day 1 (birth), and Months 2, 6, and 12
GMC of Serum RSV-F Binding Antibodies in Infant Participants
Time frame: Day 1 (birth), and Months 2, 6, and 12
This study is completed, as verified in Jun 2026. You cannot join it, but the record below documents what was studied.
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ModernaTX, Inc.