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A Study of mRNA-1345 Vaccine Targeting Respiratory Syncytial Virus in Pregnant Women and in Infants Born to Vaccinated Mothers

A Phase 2, Randomized, Observer-Blind, Placebo-Controlled, Dose-Escalation Study to Evaluate the Reactogenicity, Safety, and Immunogenicity of mRNA-1345, an mRNA Vaccine Targeting Respiratory Syncytial Virus, in Pregnant Women, and Safety and Immunogenicity in Infants Born to Vaccinated Mothers

Status
Active, not recruiting
Phases
Phase 2
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT06143046
Enrollment
360
Registered
2023-11-22
Start date
2023-11-15
Completion date
2026-05-27
Last updated
2026-02-05

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Respiratory Syncytial Virus

Keywords

mRNA-1345, RSV vaccine, Viral Diseases, Messenger RNA, Moderna

Brief summary

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.

Interventions

BIOLOGICALmRNA-1345

Sterile liquid for injection

BIOLOGICALPlacebo

0.9% sodium chloride (normal saline) injection

Sponsors

ModernaTX, Inc.
Lead SponsorINDUSTRY

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)

Masking description

Observer-blind study

Eligibility

Sex/Gender
ALL
Age
0 Years to 40 Years
Healthy volunteers
Yes

Inclusion criteria

Key Inclusion Criteria: Maternal Participants * Are adults ≥18 years to \<40 years of age inclusive, at the time of signing the informed consent. * Will be 28 to 36 weeks pregnant at the time of vaccination (confirmed by an obstetric ultrasound report). * Intend to deliver at a maternity unit where study procedures can be performed. * Are willing and able to attend all study visits, to undergo all study procedures/or have their infant undergo all study procedures, and to comply with study requirements, including a means of communication (for example, phone, text message or email) with study site staff. * Have engaged with local antenatal care and will continue to do so through the remainder of their pregnancy. * Have had an antenatal obstetric ultrasound at ≥18 weeks of pregnancy or be willing to have an antenatal obstetric ultrasound at Screening if not already conducted. Specific inclusion criteria for Japanese pregnant women: * Japanese participants are defined as individuals born in Japan, with both parents and 4 grandparents who were born in Japan. Infant Participants * Have consent from infant participant's parent(s)/legally authorized representative (LAR) if required by local regulations. Key

Exclusion criteria

Maternal Participants * Acutely ill or febrile (temperature ≥38.0 degrees Celsius \[℃\]/100.4 degrees Fahrenheit \[°F\]) within 72 hours prior to or at the Screening Visit or Day 1. * Reported history of anaphylaxis or severe hypersensitivity reaction after receipt of any mRNA vaccine or therapeutic or any components of an mRNA-1345 vaccine. * Any medical, psychiatric, or occupational condition, including reported history of drug or alcohol abuse, that, in the opinion of the Investigator, might pose additional risk due to participation in the study or could interfere with the interpretation of study results. * Have conditions in the current pregnancy or in previous pregnancies that may affect participant safety, assessment of safety endpoints, assessment of immune response, or adherence to study procedures. * Received or plans to receive any mRNA vaccine or COVID-19 vaccine within 4 weeks before or after Day 1 and/or any other nonstudy vaccine within 2 weeks before or after Day 1. * Previous vaccination with any licensed or investigational RSV vaccine or planned receipt during study participation. * Intend for their infant to receive RSV monoclonal antibodies after delivery. Infant Participants * Is a child who has been placed under the control or protection of an agency, organization, institution, or entity by the courts, the government, or a government body acting in accordance with powers conferred on them by laws and regulation (for example, foster care). This does not include a child who is adopted or has an appointed LAR. Other inclusion and

Design outcomes

Primary

MeasureTime frameDescription
Number of Infant Participants With Birth OutcomesDay 1 (birth) to Month 12Birth outcomes will include gestational age and anthropometric measurements.
Number of Maternal Participants with Serious Adverse Events (SAEs)Day 1 to Month 12 (12 months postdelivery)
Number of Maternal Participants with AEs Leading to DiscontinuationDay 1 to Month 12 (12 months postdelivery)
Number of Maternal Participants With Pregnancy OutcomesDay 1 to Month 12 (12 months postdelivery)Pregnancy outcomes will include stillbirth, live birth, vaginal delivery, and cesarean section delivery.
Number of Infant Participants with MAAEsDay 1 (birth) to Month 12
Number of Infant Participants with AESIsDay 1 (birth) to Month 12
Number of Infant Participants with SAEsDay 1 (birth) to Month 12
Number of Maternal Participants with Solicited Local and Systemic Adverse Reactions (ARs)Up to Day 7 (7 days post vaccination)
Number of Maternal Participants with Unsolicited Adverse Events (AEs)Up to Day 28 (28 days post vaccination)
Number of Maternal Participants with Medically-Attended AEs (MAAEs)Day 1 to Month 6 (6 months postdelivery)
Number of Maternal Participants with Adverse Events of Special Interest (AESIs)Day 1 to Month 12 (12 months postdelivery)

Secondary

MeasureTime frame
Geometric Mean Titer (GMT) of Serum RSV-A and RSV-B Neutralizing Antibodies in Maternal ParticipantsDay 1, Day 29, delivery, and Month 6 (6 months postdelivery)
Geometric Mean Concentration (GMC) of Serum RSV-F Binding Antibodies in Maternal ParticipantsDay 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 ParticipantsDay 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 ConcentrationsBaseline up to Month 6 (6 months postdelivery)
GMT of Serum RSV-A and RSV-B Neutralizing Antibodies in Infant ParticipantsDay 1 (birth), and Months 2, 6, and 12
GMC of Serum RSV-F Binding Antibodies in Infant ParticipantsDay 1 (birth), and Months 2, 6, and 12

Countries

Canada, Chile, Denmark, Japan, Panama, South Africa, United Kingdom, United States

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 6, 2026