A Phase 2/3 interventional study of Placebo and mRNA-1345 in Respiratory Syncytial Virus, sponsored by ModernaTX, Inc.. Completed at 269 sites in 23 countries. Open to participants aged 60 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-09-29.
Sponsored by ModernaTX, Inc. · Phase 2/3, Interventional, and Prevention
The main purpose of Part A of this study is to evaluate the safety and tolerability of mRNA-1345 vaccine and to demonstrate the efficacy of a single dose of mRNA-1345 vaccine in the prevention of a first episode of RSV-associated lower respiratory tract disease (RSV-LRTD) as compared with placebo from 14 days postinjection through 12 months.
The main purpose of Part B of this study is to evaluate the safety, tolerability and immunogenicity of a booster dose (BD) of mRNA-1345 administered 24 months after the primary dose.
The study will be conducted in 2 phases: Phase 2 and Phase 3. In the Part A Phase 2 segment, up to 2,000 participants will be randomly assigned to receive a single injection of either mRNA-1345 vaccine at the selected dose or placebo in a 1:1 randomization ratio.
In the Part A Phase 3 segment, approximately 35,000 participants will be randomly assigned to receive a single injection of either mRNA-1345 vaccine at the selected dose or placebo in a 1:1 randomization ratio.
In the Part B substudy, 1500 participants who received a dose of mRNA-1345 in Part A Phase 3 will be randomly assigned in a 2:1 randomization ratio to receive a single BD injection of either mRNA-1345 at the selected dose or placebo.
914 studies on the registry are indexed under Virus Diseases; 110 are open to participants now.
This study's enrollment of 36,814 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 (Part A):
Key Inclusion Criteria (Part B):
Key Exclusion Criteria (Part A):
Key Exclusion Criteria (Part B):
Other inclusion and/or exclusion criteria may apply.
Single injection of mRNA-1345 on Day 1.
Drug: mRNA-1345
Single injection of mRNA-1345 matching-placebo on Day 1.
Drug: Placebo
Single injection of mRNA-1345 on BD Day 1.
Drug: mRNA-1345
0.9% sodium chloride (normal saline) injection
Sterile liquid for injection
Part A: Number of Participants With Any Solicited Adverse Reactions (ARs) (Solicited Local and/or Systemic ARs)
Solicited ARs were collected in an electronic diary (eDiary). Local ARs: injection site pain, erythema (redness), swelling/induration (hardness); and axillary (underarm) swelling or tenderness ipsilateral to the side of injection. Systemic ARs: fever, headache, fatigue, myalgia, arthralgia, nausea/vomiting, and chills. Note, not all solicited ARs were considered adverse events (AEs). Investigator reviewed whether the solicited AR was also to be recorded as an AE. A summary of serious AEs (SAEs) and nonserious AEs ("Other"), regardless of causality, is located in the "Reported Adverse Events" section.
Time frame: Up to 7 days postinjection
Part B: Number of Participants With Solicited Local and Systemic ARs
Solicited ARs were recorded daily using electronic diaries (eDiaries). Local ARs: injection site pain, erythema (redness), swelling/induration (hardness); and axillary (underarm) swelling or tenderness ipsilateral to the side of injection. Systemic ARs: fever, headache, fatigue, myalgia, arthralgia, nausea/vomiting, and chills. Note, not all solicited ARs were considered adverse events (AEs). Investigator reviewed whether the solicited AR was also to be recorded as an AE. A summary of all Serious Adverse Events (SAEs) and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.
Time frame: Up to 7 days post-BD injection
Part A: Number of Participants With Unsolicited Adverse Events (AEs)
An unsolicited AE was defined as any AE reported by the participant that was not specified as a solicited AR in the protocol. An AE was defined as any untoward medical occurrence associated with the use of a drug in humans, whether or not considered drug related. A summary of all SAEs and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.
Time frame: Up to 28 days postinjection
Part B: Number of Participants With Unsolicited AEs
An unsolicited AE was defined as any AE reported by the participant that was not specified as a solicited AR in the protocol. An AE was defined as any untoward medical occurrence associated with the use of a drug in humans, whether or not considered drug related. A summary of all SAEs and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.
Time frame: Up to 28 days post-BD injection
Part A: Number of Participants With Medically Attended AEs (MAAEs), Adverse Events of Special Interest (AESIs), Serious Adverse Events (SAEs), and AEs Leading to Study Discontinuation
MAAEs were AEs that led to an unscheduled visit to a healthcare provider. AESIs were AEs (serious or nonserious) of scientific and medical concern specific to the Sponsor's product or program for which ongoing monitoring and immediate notification by the investigator to the Sponsor was required. SAEs were AEs that resulted in death, were life threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions, a congenital anomaly or birth defect, or was a medically important event. A summary of all SAEs and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.
Time frame: Up to 24 months postinjection
Part B: Number of Participants With MAAEs, AESIs, SAEs, and AEs Leading to Study Discontinuation
MAAEs were AEs that led to an unscheduled visit to a healthcare provider. AESIs were AEs (serious or nonserious) of scientific and medical concern specific to the Sponsor's product or program for which ongoing monitoring and immediate notification by the investigator to the Sponsor was required. SAEs were AEs that resulted in death, were life threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions, a congenital anomaly or birth defect, or was a medically important event. A summary of all SAEs and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.
Time frame: Up to BD Day 181
Part A: Number of Participants With Respiratory Syncytial Virus- Associated Lower RSV-LRTD With 2 or More Symptoms From 14 Days Postinjection up to 12 Months Postinjection
RSV-LRTD: Reverse transcriptase polymerase chain reaction (RT PCR) confirmed RSV infection PLUS new or worsening of ≥2 of the following symptoms: shortness of breath, cough and/or fever (≥37.8 degrees Celsius \[°C\]), wheezing and/or rales and/or rhonchi, sputum production, tachypnea (≥20 breaths/minute or increase of ≥ 2 breaths/minute from baseline measurement in those who had baseline tachypnea), hypoxemia (new oxygen saturation ≤93% or new or increasing use of supplemental oxygen), pleuritic chest pain for ≥24 hours.
Time frame: From 14 days postinjection up to 12 months postinjection
Part A: Number of Participants With RSV-LRTD With 3 or More Symptoms From 14 Days Postinjection up to 12 Months Postinjection
RSV-LRTD: RT PCR confirmed RSV infection PLUS new or worsening of ≥3 of the following symptoms: shortness of breath, cough and/or fever (≥37.8°C), wheezing and/or rales and/or rhonchi, sputum production, tachypnea (≥20 breaths/minute or increase of ≥ 2 breaths/minute from baseline measurement in those who had baseline tachypnea), hypoxemia (new oxygen saturation ≤93% or new or increasing use of supplemental oxygen), pleuritic chest pain for ≥24 hours.
Time frame: From 14 days postinjection up to 12 months postinjection
Part B: Geometric Mean Titer (GMT) of Serum Respiratory Syncytial Virus Subtype A (RSV-A) and Respiratory Syncytial Virus Subtype B (RSV-B) Neutralizing Antibodies (nAb) at BD Day 29 Compared to Primary Dose Day 29
Antibody values reported as below lower limit of quantification (LLOQ) replaced by 0.5 \* LLOQ. Values greater than upper limit of quantification (ULOQ) replaced by ULOQ. LLOQ = 13 international units (IU)/milliliter (mL), ULOQ = 259061 IU/mL for RSV-A nAb. LLOQ = 10, ULOQ = 112476 for RSV-B nAb. Part B Per-protocol (PP) Set: all Part B randomized participants who received both Parts A and B assigned study intervention doses, had RSV immunogenicity titer results at pre-Primary Dose (baseline), had RSV immunogenicity titer results at Primary Dose Day 29, had at least 1 valid result at Revaccination Day 29, and had no major protocol deviations affecting the primary immunogenicity outcomes as determined prior to database lock and unblinding. Participants were analyzed according to the study intervention group to which they were randomized.
Time frame: Primary Dose Day 29 and BD Day 29
Part A: Number of Participants With RSV-Associated Acute Respiratory Disease (RSV-ARD) From 14 Days Postinjection up to 12 Months Postinjection
RSV-ARD: RT-PCR-confirmed RSV infection PLUS an acute symptomatic respiratory disease manifesting as new or worsening of 1 or more of cough, stuffy nose, runny nose, sore throat, fever (≥37.8°C), shortness of breath, observed tachypnea (≥20 breaths/minute or increase of ≥2 breaths/minute from baseline in those who have baseline tachypnea), hypoxemia (new oxygen saturation ≤ 93%, or new or increasing use of supplemental oxygen), wheezing, sputum production, hoarseness, sinus pain, chills, pleuritic chest pain for at least 24 hours.
Time frame: From 14 days postinjection up to 12 months postinjection
Part A: Number of Participants With Hospitalization Associated With Protocol-defined RSV-ARD or RSV-LRTD From 14 Days Postinjection up to 12 Months Postinjection
A case of first hospitalization associated with protocol-defined RSV-ARD or RSV-LRTD was defined if: (a) The investigator assessed that an event was a confirmed diagnosis of RSV-LRTD or RSV-ARD and that required inpatient or prolongation of existing hospitalization; (b) a protocol-defined RSV-LRTD/RSV-ARD occurred; (c) date of protocol-defined RSV-LRTD/RSV-ARD was within 14 days prior or during hospitalization. RSV-ARD defined in Outcome Measure #10 and RSV-LRTD defined in Outcome Measure #7 above.
Time frame: From 14 days postinjection up to 12 months postinjection
Part A: Number of Participants With All-Cause Hospitalizations From 14 Days Postinjection up to 12 Months Postinjection
An all-cause hospitalization was defined as any reported hospitalization which was collected as inpatient or prolongation of existing hospitalization in the electronic case report form (eCRF) AE form.
Time frame: From 14 days postinjection up to 12 months postinjection
Part A: Number of Participants With All-Cause LRTD From 14 Days Postinjection up to 12 Months Postinjection
All-cause LRTD: New or worsening of ≥2 of following symptoms: shortness of breath, cough and/or fever (≥37.8°C), wheezing and/or rales and/or rhonchi, sputum production, tachypnea (≥20 breaths/minute or increase of ≥2 breaths/minute from baseline measurement in those who had baseline tachypnea), hypoxemia (new oxygen saturation ≤93% or new or increasing use of supplemental oxygen), pleuritic chest pain for ≥24 hours with any or no RT-PCR result. All-cause LRTD was derived based on eligible LRTD symptoms onset within a respiratory illness episode.
Time frame: From 14 days postinjection up to 12 months postinjection
Part A: Number of Participants With RSV-LRTD With 3 or More Symptoms From 14 Days Postinjection up to 24 Months Postinjection
RSV-LRTD: RT PCR confirmed RSV infection PLUS new or worsening of ≥3 of the following symptoms: shortness of breath, cough and/or fever (≥37.8°C), wheezing and/or rales and/or rhonchi, sputum production, tachypnea (≥20 breaths/minute or increase of ≥ 2 breaths/minute from baseline measurement in those who had baseline tachypnea), hypoxemia (new oxygen saturation ≤93% or new or increasing use of supplemental oxygen), pleuritic chest pain for ≥24 hours.
Time frame: From 14 days postinjection up to 24 months postinjection
Part A: Number of Participants With RSV-LRTD With 2 or More Symptoms From 14 Days Postinjection up to 24 Months Postinjection
RSV-LRTD: RT PCR confirmed RSV infection PLUS new or worsening of ≥2 of the following symptoms: shortness of breath, cough and/or fever (≥37.8°C), wheezing and/or rales and/or rhonchi, sputum production, tachypnea (≥20 breaths/minute or increase of ≥ 2 breaths/minute from baseline measurement in those who had baseline tachypnea), hypoxemia (new oxygen saturation ≤93% or new or increasing use of supplemental oxygen), pleuritic chest pain for ≥24 hours.
Time frame: From 14 days postinjection up to 24 months postinjection
Part A: Number of Participants With RSV-LRTD With 2 or More Symptoms by RSV Subtype A and RSV Subtype B From 14 Days Postinjection up to 12 Months Postinjection
RSV-LRTD: RT PCR confirmed RSV infection PLUS new or worsening of ≥2 of the following symptoms: shortness of breath, cough and/or fever (≥37.8°C), wheezing and/or rales and/or rhonchi, sputum production, tachypnea (≥20 breaths/minute or increase of ≥ 2 breaths/minute from baseline measurement in those who had baseline tachypnea), hypoxemia (new oxygen saturation ≤93% or new or increasing use of supplemental oxygen), pleuritic chest pain for ≥24 hours.
Time frame: From 14 days postinjection up to 12 months postinjection
Part A: Number of Participants With RSV-LRTD With 3 or More Symptoms by RSV Subtype A and RSV Subtype B From 14 Days Postinjection up to 12 Months Postinjection
RSV-LRTD: RT PCR confirmed RSV infection PLUS new or worsening of ≥3 of the following symptoms: shortness of breath, cough and/or fever (≥37.8°C), wheezing and/or rales and/or rhonchi, sputum production, tachypnea (≥20 breaths/minute or increase of ≥ 2 breaths/minute from baseline measurement in those who had baseline tachypnea), hypoxemia (new oxygen saturation ≤93% or new or increasing use of supplemental oxygen), pleuritic chest pain for ≥24 hours.
Time frame: From 14 days postinjection up to 12 months postinjection
Part A: Number of Participants With First Hospitalization Associated With Protocol-defined RSV-ARD or RSV-LRTD From 14 Days Postinjection up to 24 Months Postinjection
A case of first hospitalization associated with protocol-defined RSV-ARD or RSV-LRTD was defined if: (a) The investigator assessed that an event was a confirmed diagnosis of RSV-LRTD or RSV-ARD and that required inpatient or prolongation of existing hospitalization; (b) a protocol-defined RSV-LRTD/RSV-ARD occurred; (c) date of protocol-defined RSV-LRTD/RSV-ARD was within 14 days prior or during hospitalization. RSV-ARD defined in Outcome Measure #10 and RSV-LRTD defined in Outcome Measure #7 above.
Time frame: From 14 days postinjection up to 24 months postinjection
Part A: Change in Total Frailty Score From Baseline to 12 Months and 24 Months Postinjection, Using the Edmonton Frail Scale (EFS)
The total frail score is the sum of individual scores from the 11 questions representing 9 domains included in EFS, which is a multidimensional frail assessment scale that assesses domains related to frailty including cognition, general health status, functional independence, social support, medication use, nutrition, mood, continence, and functional performance. The total frail score ranges between 0 and 17. Higher scores suggest more frailty, and the total frail score can be interpreted as: 0-3=fit, 4-5=vulnerable, 6-7=mild frail, 8-9=moderate frail, 10 or more=severe frail.
Time frame: Baseline, 12 months and 24 months postinjection
Part A: GMT of Serum RSV nAb
Antibody values reported as below LLOQ replaced by 0.5 \* LLOQ. Values greater than ULOQ replaced by ULOQ. LLOQ = 13 IU/mL, ULOQ = 259061 IU/mL for RSV-A nAb. LLOQ = 10, ULOQ = 112476 for RSV-B nAb. Part A Per-protocol Immunogenicity (PPI) Set: a randomly selected subset of participants who: a) received the assigned study drug, b) had RSV immunogenicity titer results at baseline (prior to study drug administration) and at least 1 valid result after the study drug administration at timepoint of interest, and c) had no major protocol deviation affecting the primary immunogenicity outcomes as determined prior to database lock and unblinding.
Time frame: Baseline (Day 1), Days 29, 181, 365, and 730
Part A: Geometric Mean Concentration (GMC) of Serum RSV Binding Antibodies
Antibody values reported as below LLOQ replaced by 0.5 \* LLOQ. Values greater than ULOQ replaced by ULOQ. LLOQ = 35 arbitrary unit (AU)/mL, ULOQ = 580553 AU/mL for RSV Pre-F immunoglobulin G (IgG) antibody (Ab). LLOQ = 57, ULOQ = 847551 for RSV Post-F IgG Ab. Part A PPI Set: a randomly selected subset of participants who: a) received the assigned study drug, b) had RSV immunogenicity titer results at baseline (prior to study drug administration) and at least 1 valid result after the study drug administration at timepoint of interest, and c) had no major protocol deviation affecting the primary immunogenicity outcomes as determined prior to database lock and unblinding.
Time frame: Baseline (Day 1), Days 29, 181, 365, and 730
Part A: Percentage of Participants With Seroresponse in RSV nAb
Seroresponse was defined as a change from below the LLOQ to equal or above 4 \* LLOQ, or at least a 4-fold increase if baseline was equal to or above the LLOQ. Part A PPI Set: a randomly selected subset of participants who: a) received the assigned study drug, b) had RSV immunogenicity titer results at baseline (prior to study drug administration) and at least 1 valid result after the study drug administration at timepoint of interest, and c) had no major protocol deviation affecting the primary immunogenicity outcomes as determined prior to database lock and unblinding.
Time frame: Days 29, 181, 365, and 730
Part A: Geometric Mean Fold-Rise (GMFR) of Postbaseline/Baseline Antibody Titers
Antibody values reported as below LLOQ replaced by 0.5 \* LLOQ. Values greater than ULOQ replaced by ULOQ. LLOQ = 13 IU/mL, ULOQ = 259061 IU/mL for RSV-A nAb. LLOQ = 10, ULOQ = 112476 for RSV-B nAb. Part A PPI Set: a randomly selected subset of participants who: a) received the assigned study drug, b) had RSV immunogenicity titer results at baseline (prior to study drug administration) and at least 1 valid result after the study drug administration at timepoint of interest, and c) had no major protocol deviation affecting the primary immunogenicity outcomes as determined prior to database lock and unblinding.
Time frame: Days 29, 181, 365, and 730
Part A: Percentage of Participants With ≥2-fold Increases in Antibody Titers From Baseline
A ≥2-fold increase from baseline was defined as a change from below the LLOQ to equal or above 2 \* LLOQ, or at least a 2-fold increase if baseline was equal to or above the LLOQ. Part A PPI Set: a randomly selected subset of participants who: a) received the assigned study drug, b) had RSV immunogenicity titer results at baseline (prior to study drug administration) and at least 1 valid result after the study drug administration at timepoint of interest, and c) had no major protocol deviation affecting the primary immunogenicity outcomes as determined prior to database lock and unblinding.
Time frame: Days 29, 181, 365, and 730
Part B: Percentage of Participants With Seroresponse of Serum RSV-A and RSV-B nAb at BD Day 29 Compared to Primary Dose Day 29
Seroresponse was defined as a post-primary dose or post-revaccination titer ≥4 \* LLOQ if Baseline was \<LLOQ or a ≥4-fold increase from baseline if baseline was ≥LLOQ. Part B PP Set: all Part B randomized participants who received both Parts A and B assigned study intervention doses, had RSV immunogenicity titer results at pre-Primary Dose (baseline), had RSV immunogenicity titer results at Primary Dose Day 29, had at least 1 valid result at Revaccination Day 29, and had no major protocol deviations affecting the primary immunogenicity outcomes as determined prior to database lock and unblinding. Participants were analyzed according to the study intervention group to which they were randomized.
Time frame: Primary Dose Day 29 and BD Day 29
Part B: GMT of Serum RSV-A and RSV-B nAb at BD Day 1 and BD Day 181
Antibody values reported as below LLOQ replaced by 0.5 \* LLOQ. Values greater than ULOQ replaced by ULOQ. LLOQ = 13 IU/mL, ULOQ = 259061 IU/mL for RSV-A nAb. LLOQ = 10, ULOQ = 112476 for RSV-B nAb. Part B PP Set: all Part B randomized participants who received both Parts A and B assigned study intervention doses, had RSV immunogenicity titer results at pre-Primary Dose (baseline), had RSV immunogenicity titer results at Primary Dose Day 29, had at least 1 valid result at Revaccination Day 29, and had no major protocol deviations affecting the primary immunogenicity outcomes as determined prior to database lock and unblinding. Participants were analyzed according to the study intervention group to which they were randomized.
Time frame: BD Day 1 and BD Day 181
Part B: GMFR of Serum RSV-A and RSV-B NAb From Pre-primary Dose (Baseline)
Antibody values reported as below LLOQ replaced by 0.5 \* LLOQ. Values greater than ULOQ replaced by ULOQ. LLOQ = 13 IU/mL, ULOQ = 259061 IU/mL for RSV-A nAb. LLOQ = 10, ULOQ = 112476 for RSV-B nAb. Part B PP Set: all Part B randomized participants who received both Parts A and B assigned study intervention doses, had RSV immunogenicity titer results at pre-Primary Dose (baseline), had RSV immunogenicity titer results at Primary Dose Day 29, had at least 1 valid result at Revaccination Day 29, and had no major protocol deviations affecting the primary immunogenicity outcomes as determined prior to database lock and unblinding. Participants were analyzed according to the study intervention group to which they were randomized.
Time frame: BD Day 1, BD Day 29, and BD Day 181
Part B: Percentage of Participants With Seroresponse of Serum RSV-A and RSV-B Neutralizing Antibodies From Pre-primary Dose (Baseline)
Seroresponse was defined as a post-primary dose or post-revaccination titer ≥4 \* LLOQ if Baseline was \<LLOQ or a ≥4-fold increase from baseline if baseline was ≥LLOQ. Part B PP Set: all Part B randomized participants who received both Parts A and B assigned study intervention doses, had RSV immunogenicity titer results at pre-Primary Dose (baseline), had RSV immunogenicity titer results at Primary Dose Day 29, had at least 1 valid result at Revaccination Day 29, and had no major protocol deviations affecting the primary immunogenicity outcomes as determined prior to database lock and unblinding. Participants were analyzed according to the study intervention group to which they were randomized.
Time frame: BD Day 1, BD Day 29, and BD Day 181
| Milestone | Part A: Placebo | Part A: mRNA-1345 | Part B: Placebo | Part B: mRNA-1345 |
|---|---|---|---|---|
| Started | 18387 | 18427 | 0 | 0 |
| Safety set | 18316 | 18369 | 0 | 0 |
| Solicited safety set | 18102 | 18174 | 0 | 0 |
| Per-protocol efficacy (ppe) set | 18120 | 18164 | 0 | 0 |
| Completed | 15605 | 15726 | 0 | 0 |
| Not completed | 2782 | 2701 | 0 | 0 |
| Withdrew: Adverse event | 29 | 20 | 0 | 0 |
| Withdrew: Death | 305 | 300 | 0 | 0 |
| Withdrew: Lost to follow-up | 849 | 871 | 0 | 0 |
| Withdrew: Non-compliance with study drug | 2 | 1 | 0 | 0 |
| Withdrew: Physician decision | 98 | 81 | 0 | 0 |
| Withdrew: Protocol violation | 47 | 32 | 0 | 0 |
| Withdrew: Withdrawal by subject | 922 | 859 | 0 | 0 |
| Withdrew: Other than specified | 530 | 537 | 0 | 0 |
| Milestone | Part A: Placebo | Part A: mRNA-1345 | Part B: Placebo | Part B: mRNA-1345 |
|---|---|---|---|---|
| Started | 0 | 0 | 505 | 1005 |
| Received revaccination injection | 0 | 0 | 504 | 998 |
| Solicited safety set | 0 | 0 | 503 | 995 |
| Per-protocol (pp) set | 0 | 0 | 489 | 956 |
| Completed | 0 | 0 | 480 | 954 |
| Not completed | 0 | 0 | 25 | 51 |
| Withdrew: Death | 0 | 0 | 1 | 0 |
| Withdrew: Lost to follow-up | 0 | 0 | 6 | 12 |
| Withdrew: Withdrawal by subject | 0 | 0 | 3 | 9 |
| Withdrew: Other than specified | 0 | 0 | 15 | 30 |
Solicited ARs were collected in an electronic diary (eDiary). Local ARs: injection site pain, erythema (redness), swelling/induration (hardness); and axillary (underarm) swelling or tenderness ipsilateral to the side of injection. Systemic ARs: fever, headache, fatigue, myalgia, arthralgia, nausea/vomiting, and chills. Note, not all solicited ARs were considered adverse events (AEs). Investigator reviewed whether the solicited AR was also to be recorded as an AE. A summary of serious AEs (SAEs) and nonserious AEs ("Other"), regardless of causality, is located in the "Reported Adverse Events" section.
| Participants | Part A: Placebo | Part A: mRNA-1345 |
|---|---|---|
| Part A: Number of Participants With Any Solicited Adverse Reactions (ARs) (Solicited Local and/or Systemic ARs) | 6975 | 12383 |
Solicited ARs were recorded daily using electronic diaries (eDiaries). Local ARs: injection site pain, erythema (redness), swelling/induration (hardness); and axillary (underarm) swelling or tenderness ipsilateral to the side of injection. Systemic ARs: fever, headache, fatigue, myalgia, arthralgia, nausea/vomiting, and chills. Note, not all solicited ARs were considered adverse events (AEs). Investigator reviewed whether the solicited AR was also to be recorded as an AE. A summary of all Serious Adverse Events (SAEs) and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.
| Participants | Part B: Placebo | Part B: mRNA-1345 |
|---|---|---|
| Part B: Number of Participants With Solicited Local and Systemic ARs | 194 | 748 |
An unsolicited AE was defined as any AE reported by the participant that was not specified as a solicited AR in the protocol. An AE was defined as any untoward medical occurrence associated with the use of a drug in humans, whether or not considered drug related. A summary of all SAEs and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.
| Participants | Part A: Placebo | Part A: mRNA-1345 |
|---|---|---|
| Part A: Number of Participants With Unsolicited Adverse Events (AEs) | 3472 | 3841 |
An unsolicited AE was defined as any AE reported by the participant that was not specified as a solicited AR in the protocol. An AE was defined as any untoward medical occurrence associated with the use of a drug in humans, whether or not considered drug related. A summary of all SAEs and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.
| Participants | Part B: Placebo | Part B: mRNA-1345 |
|---|---|---|
| Part B: Number of Participants With Unsolicited AEs | 75 | 123 |
MAAEs were AEs that led to an unscheduled visit to a healthcare provider. AESIs were AEs (serious or nonserious) of scientific and medical concern specific to the Sponsor's product or program for which ongoing monitoring and immediate notification by the investigator to the Sponsor was required. SAEs were AEs that resulted in death, were life threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions, a congenital anomaly or birth defect, or was a medically important event. A summary of all SAEs and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.
| Participants | Part A: Placebo | Part A: mRNA-1345 |
|---|---|---|
| MAAEs | 10995 | 11313 |
| AESIs | 154 | 158 |
| SAEs | 2745 | 2773 |
| AEs Leading to Study Discontinuation | 335 | 319 |
MAAEs were AEs that led to an unscheduled visit to a healthcare provider. AESIs were AEs (serious or nonserious) of scientific and medical concern specific to the Sponsor's product or program for which ongoing monitoring and immediate notification by the investigator to the Sponsor was required. SAEs were AEs that resulted in death, were life threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions, a congenital anomaly or birth defect, or was a medically important event. A summary of all SAEs and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.
| Participants | Part B: Placebo | Part B: mRNA-1345 |
|---|---|---|
| MAAEs | 131 | 226 |
| AESIs | 3 | 2 |
| SAEs | 26 | 29 |
| AEs Leading to Study Discontinuation | 1 | 0 |
RSV-LRTD: Reverse transcriptase polymerase chain reaction (RT PCR) confirmed RSV infection PLUS new or worsening of ≥2 of the following symptoms: shortness of breath, cough and/or fever (≥37.8 degrees Celsius \[°C\]), wheezing and/or rales and/or rhonchi, sputum production, tachypnea (≥20 breaths/minute or increase of ≥ 2 breaths/minute from baseline measurement in those who had baseline tachypnea), hypoxemia (new oxygen saturation ≤93% or new or increasing use of supplemental oxygen), pleuritic chest pain for ≥24 hours.
| Participants | Part A: Placebo | Part A: mRNA-1345 |
|---|---|---|
| Part A: Number of Participants With Respiratory Syncytial Virus- Associated Lower RSV-LRTD With 2 or More Symptoms From 14 Days Postinjection up to 12 Months Postinjection | 55 | 9 |
RSV-LRTD: RT PCR confirmed RSV infection PLUS new or worsening of ≥3 of the following symptoms: shortness of breath, cough and/or fever (≥37.8°C), wheezing and/or rales and/or rhonchi, sputum production, tachypnea (≥20 breaths/minute or increase of ≥ 2 breaths/minute from baseline measurement in those who had baseline tachypnea), hypoxemia (new oxygen saturation ≤93% or new or increasing use of supplemental oxygen), pleuritic chest pain for ≥24 hours.
| Participants | Part A: Placebo | Part A: mRNA-1345 |
|---|---|---|
| Part A: Number of Participants With RSV-LRTD With 3 or More Symptoms From 14 Days Postinjection up to 12 Months Postinjection | 17 | 3 |
Antibody values reported as below lower limit of quantification (LLOQ) replaced by 0.5 \* LLOQ. Values greater than upper limit of quantification (ULOQ) replaced by ULOQ. LLOQ = 13 international units (IU)/milliliter (mL), ULOQ = 259061 IU/mL for RSV-A nAb. LLOQ = 10, ULOQ = 112476 for RSV-B nAb. Part B Per-protocol (PP) Set: all Part B randomized participants who received both Parts A and B assigned study intervention doses, had RSV immunogenicity titer results at pre-Primary Dose (baseline), had RSV immunogenicity titer results at Primary Dose Day 29, had at least 1 valid result at Revaccination Day 29, and had no major protocol deviations affecting the primary immunogenicity outcomes as determined prior to database lock and unblinding. Participants were analyzed according to the study intervention group to which they were randomized.
| IU/mL | mRNA-1345 Primary Vaccination | mRNA-1345 Revaccination |
|---|---|---|
| RSV-A | 17157.48 (16004.77 to 18393.22) | 12339.87 (11538.56 to 13196.82) |
| RSV-B | 5665.14 (5294.89 to 6061.28) | 4005.79 (3771.68 to 4254.43) |
RSV-ARD: RT-PCR-confirmed RSV infection PLUS an acute symptomatic respiratory disease manifesting as new or worsening of 1 or more of cough, stuffy nose, runny nose, sore throat, fever (≥37.8°C), shortness of breath, observed tachypnea (≥20 breaths/minute or increase of ≥2 breaths/minute from baseline in those who have baseline tachypnea), hypoxemia (new oxygen saturation ≤ 93%, or new or increasing use of supplemental oxygen), wheezing, sputum production, hoarseness, sinus pain, chills, pleuritic chest pain for at least 24 hours.
| Participants | Part A: Placebo | Part A: mRNA-1345 |
|---|---|---|
| Part A: Number of Participants With RSV-Associated Acute Respiratory Disease (RSV-ARD) From 14 Days Postinjection up to 12 Months Postinjection | 82 | 26 |
A case of first hospitalization associated with protocol-defined RSV-ARD or RSV-LRTD was defined if: (a) The investigator assessed that an event was a confirmed diagnosis of RSV-LRTD or RSV-ARD and that required inpatient or prolongation of existing hospitalization; (b) a protocol-defined RSV-LRTD/RSV-ARD occurred; (c) date of protocol-defined RSV-LRTD/RSV-ARD was within 14 days prior or during hospitalization. RSV-ARD defined in Outcome Measure #10 and RSV-LRTD defined in Outcome Measure #7 above.
| Participants | Part A: Placebo | Part A: mRNA-1345 |
|---|---|---|
| Part A: Number of Participants With Hospitalization Associated With Protocol-defined RSV-ARD or RSV-LRTD From 14 Days Postinjection up to 12 Months Postinjection | 2 | 0 |
An all-cause hospitalization was defined as any reported hospitalization which was collected as inpatient or prolongation of existing hospitalization in the electronic case report form (eCRF) AE form.
| Participants | Part A: Placebo | Part A: mRNA-1345 |
|---|---|---|
| Part A: Number of Participants With All-Cause Hospitalizations From 14 Days Postinjection up to 12 Months Postinjection | 1564 | 1580 |
All-cause LRTD: New or worsening of ≥2 of following symptoms: shortness of breath, cough and/or fever (≥37.8°C), wheezing and/or rales and/or rhonchi, sputum production, tachypnea (≥20 breaths/minute or increase of ≥2 breaths/minute from baseline measurement in those who had baseline tachypnea), hypoxemia (new oxygen saturation ≤93% or new or increasing use of supplemental oxygen), pleuritic chest pain for ≥24 hours with any or no RT-PCR result. All-cause LRTD was derived based on eligible LRTD symptoms onset within a respiratory illness episode.
| Participants | Part A: Placebo | Part A: mRNA-1345 |
|---|---|---|
| Part A: Number of Participants With All-Cause LRTD From 14 Days Postinjection up to 12 Months Postinjection | 5806 | 5762 |
RSV-LRTD: RT PCR confirmed RSV infection PLUS new or worsening of ≥3 of the following symptoms: shortness of breath, cough and/or fever (≥37.8°C), wheezing and/or rales and/or rhonchi, sputum production, tachypnea (≥20 breaths/minute or increase of ≥ 2 breaths/minute from baseline measurement in those who had baseline tachypnea), hypoxemia (new oxygen saturation ≤93% or new or increasing use of supplemental oxygen), pleuritic chest pain for ≥24 hours.
| Participants | Part A: Placebo | Part A: mRNA-1345 |
|---|---|---|
| Part A: Number of Participants With RSV-LRTD With 3 or More Symptoms From 14 Days Postinjection up to 24 Months Postinjection | 123 | 61 |
RSV-LRTD: RT PCR confirmed RSV infection PLUS new or worsening of ≥2 of the following symptoms: shortness of breath, cough and/or fever (≥37.8°C), wheezing and/or rales and/or rhonchi, sputum production, tachypnea (≥20 breaths/minute or increase of ≥ 2 breaths/minute from baseline measurement in those who had baseline tachypnea), hypoxemia (new oxygen saturation ≤93% or new or increasing use of supplemental oxygen), pleuritic chest pain for ≥24 hours.
| Participants | Part A: Placebo | Part A: mRNA-1345 |
|---|---|---|
| Part A: Number of Participants With RSV-LRTD With 2 or More Symptoms From 14 Days Postinjection up to 24 Months Postinjection | 286 | 161 |
RSV-LRTD: RT PCR confirmed RSV infection PLUS new or worsening of ≥2 of the following symptoms: shortness of breath, cough and/or fever (≥37.8°C), wheezing and/or rales and/or rhonchi, sputum production, tachypnea (≥20 breaths/minute or increase of ≥ 2 breaths/minute from baseline measurement in those who had baseline tachypnea), hypoxemia (new oxygen saturation ≤93% or new or increasing use of supplemental oxygen), pleuritic chest pain for ≥24 hours.
| Participants | Part A: Placebo | Part A: mRNA-1345 |
|---|---|---|
| RSV-A | 36 | 3 |
| RSV-B | 19 | 6 |
RSV-LRTD: RT PCR confirmed RSV infection PLUS new or worsening of ≥3 of the following symptoms: shortness of breath, cough and/or fever (≥37.8°C), wheezing and/or rales and/or rhonchi, sputum production, tachypnea (≥20 breaths/minute or increase of ≥ 2 breaths/minute from baseline measurement in those who had baseline tachypnea), hypoxemia (new oxygen saturation ≤93% or new or increasing use of supplemental oxygen), pleuritic chest pain for ≥24 hours.
| Participants | Part A: Placebo | Part A: mRNA-1345 |
|---|---|---|
| RSV-A | 10 | 1 |
| RSV-B | 7 | 2 |
A case of first hospitalization associated with protocol-defined RSV-ARD or RSV-LRTD was defined if: (a) The investigator assessed that an event was a confirmed diagnosis of RSV-LRTD or RSV-ARD and that required inpatient or prolongation of existing hospitalization; (b) a protocol-defined RSV-LRTD/RSV-ARD occurred; (c) date of protocol-defined RSV-LRTD/RSV-ARD was within 14 days prior or during hospitalization. RSV-ARD defined in Outcome Measure #10 and RSV-LRTD defined in Outcome Measure #7 above.
| Participants | Part A: Placebo | Part A: mRNA-1345 |
|---|---|---|
| Part A: Number of Participants With First Hospitalization Associated With Protocol-defined RSV-ARD or RSV-LRTD From 14 Days Postinjection up to 24 Months Postinjection | 2 | 1 |
The total frail score is the sum of individual scores from the 11 questions representing 9 domains included in EFS, which is a multidimensional frail assessment scale that assesses domains related to frailty including cognition, general health status, functional independence, social support, medication use, nutrition, mood, continence, and functional performance. The total frail score ranges between 0 and 17. Higher scores suggest more frailty, and the total frail score can be interpreted as: 0-3=fit, 4-5=vulnerable, 6-7=mild frail, 8-9=moderate frail, 10 or more=severe frail.
| score on a scale | Part A: Placebo | Part A: mRNA-1345 |
|---|---|---|
| Change at Month 12 | 0.2 ± 1.79 | 0.2 ± 1.78 |
| Change at Month 24 | 0.3 ± 1.91 | 0.3 ± 1.89 |
Antibody values reported as below LLOQ replaced by 0.5 \* LLOQ. Values greater than ULOQ replaced by ULOQ. LLOQ = 13 IU/mL, ULOQ = 259061 IU/mL for RSV-A nAb. LLOQ = 10, ULOQ = 112476 for RSV-B nAb. Part A Per-protocol Immunogenicity (PPI) Set: a randomly selected subset of participants who: a) received the assigned study drug, b) had RSV immunogenicity titer results at baseline (prior to study drug administration) and at least 1 valid result after the study drug administration at timepoint of interest, and c) had no major protocol deviation affecting the primary immunogenicity outcomes as determined prior to database lock and unblinding.
| IU/mL | Part A: Placebo | Part A: mRNA-1345 |
|---|---|---|
| RSV-A: Day 1 | 2403.59 (2137.23 to 2703.15) | 2559.03 (2421.48 to 2704.39) |
| RSV-A: Day 29 | 2411.91 (2151.25 to 2704.16) | 21258.26 (20083.91 to 22501.27) |
| RSV-A: Day 181 | 2114.80 (1874.89 to 2385.41) | 7094.40 (6688.56 to 7524.87) |
| RSV-A: Day 365 | 2011.85 (1766.83 to 2290.85) | 4646.43 (4375.17 to 4934.51) |
| RSV-A: Day 730 | 2259.10 (1922.61 to 2654.49) | 3920.00 (3680.66 to 4174.90) |
| RSV-B: Day 1 | 1367.88 (1219.40 to 1534.43) | 1425.73 (1354.03 to 1501.22) |
| RSV-B: Day 29 | 1308.32 (1163.27 to 1471.45) | 7224.01 (6845.63 to 7623.30) |
| RSV-B: Day 181 | 1123.06 (1001.78 to 1259.02) | 2797.20 (2653.08 to 2949.16) |
| RSV-B: Day 365 | 1087.30 (955.94 to 1236.71) | 1993.79 (1891.72 to 2101.37) |
| RSV-B: Day 730 | 1174.89 (1022.03 to 1350.61) | 1816.21 (1713.20 to 1925.41) |
Antibody values reported as below LLOQ replaced by 0.5 \* LLOQ. Values greater than ULOQ replaced by ULOQ. LLOQ = 35 arbitrary unit (AU)/mL, ULOQ = 580553 AU/mL for RSV Pre-F immunoglobulin G (IgG) antibody (Ab). LLOQ = 57, ULOQ = 847551 for RSV Post-F IgG Ab. Part A PPI Set: a randomly selected subset of participants who: a) received the assigned study drug, b) had RSV immunogenicity titer results at baseline (prior to study drug administration) and at least 1 valid result after the study drug administration at timepoint of interest, and c) had no major protocol deviation affecting the primary immunogenicity outcomes as determined prior to database lock and unblinding.
| AU/mL | Part A: Placebo | Part A: mRNA-1345 |
|---|---|---|
| RSV Pre-F IgG: Day 1 | 10197.91 (9390.41 to 11074.85) | 10719.10 (10305.60 to 11149.19) |
| RSV Pre-F IgG: Day 29 | 10068.44 (9267.14 to 10939.01) | 81897.81 (78658.16 to 85270.89) |
| RSV Pre-F IgG: Day 181 | 11559.45 (10640.29 to 12558.00) | 36208.22 (34870.87 to 37596.87) |
| RSV Pre-F IgG: Day 365 | 11986.87 (10920.62 to 13157.22) | 26033.56 (25079.43 to 27023.99) |
| RSV Pre-F IgG: Day 730 | 12673.59 (11359.94 to 14139.14) | 22428.74 (21513.33 to 23383.10) |
| RSV Post-F IgG: Day 1 | 14188.99 (12866.04 to 15647.97) | 14405.86 (13767.81 to 15073.48) |
| RSV Post-F IgG: Day 29 | 14054.35 (12744.65 to 15498.65) | 84081.63 (80191.52 to 88160.45) |
| RSV Post-F IgG: Day 181 | 14335.77 (12948.78 to 15871.34) | 36078.03 (34477.82 to 37752.51) |
| RSV Post-F IgG: Day 365 | 14957.00 (13401.73 to 16692.77) | 26977.85 (25796.45 to 28213.36) |
| RSV Post-F IgG: Day 730 | 15681.64 (13810.96 to 17805.70) | 24413.11 (23258.27 to 25625.30) |
Seroresponse was defined as a change from below the LLOQ to equal or above 4 \* LLOQ, or at least a 4-fold increase if baseline was equal to or above the LLOQ. Part A PPI Set: a randomly selected subset of participants who: a) received the assigned study drug, b) had RSV immunogenicity titer results at baseline (prior to study drug administration) and at least 1 valid result after the study drug administration at timepoint of interest, and c) had no major protocol deviation affecting the primary immunogenicity outcomes as determined prior to database lock and unblinding.
| percentage of participants | Part A: Placebo | Part A: mRNA-1345 |
|---|---|---|
| RSV-A: Day 29 | 0.6 (0.1 to 2.2) | 74.0 (71.7 to 76.2) |
| RSV-A: Day 181 | 3.2 (1.5 to 5.7) | 32.9 (30.4 to 35.4) |
| RSV-A: Day 365 | 5.2 (3.0 to 8.4) | 19.3 (17.2 to 21.5) |
| RSV-A: Day 730 | 7.7 (4.8 to 11.5) | 15.7 (13.7 to 17.9) |
| RSV-B: Day 29 | 1.5 (0.5 to 3.5) | 56.6 (54.0 to 59.1) |
| RSV-B: Day 181 | 3.2 (1.5 to 5.8) | 19.9 (17.8 to 22.0) |
| RSV-B: Day 365 | 4.9 (2.8 to 8.0) | 10.5 (8.9 to 12.3) |
| RSV-B: Day 730 | 6.9 (4.2 to 10.6) | 9.2 (7.6 to 10.9) |
Antibody values reported as below LLOQ replaced by 0.5 \* LLOQ. Values greater than ULOQ replaced by ULOQ. LLOQ = 13 IU/mL, ULOQ = 259061 IU/mL for RSV-A nAb. LLOQ = 10, ULOQ = 112476 for RSV-B nAb. Part A PPI Set: a randomly selected subset of participants who: a) received the assigned study drug, b) had RSV immunogenicity titer results at baseline (prior to study drug administration) and at least 1 valid result after the study drug administration at timepoint of interest, and c) had no major protocol deviation affecting the primary immunogenicity outcomes as determined prior to database lock and unblinding.
| ratio | Part A: Placebo | Part A: mRNA-1345 |
|---|---|---|
| RSV-A: Day 29 | 1.00 (0.95 to 1.06) | 8.33 (7.88 to 8.80) |
| RSV-A: Day 181 | 0.88 (0.81 to 0.94) | 2.80 (2.65 to 2.96) |
| RSV-A: Day 365 | 0.84 (0.77 to 0.92) | 1.82 (1.73 to 1.92) |
| RSV-A: Day 730 | 0.94 (0.84 to 1.04) | 1.60 (1.51 to 1.69) |
| RSV-B: Day 29 | 0.96 (0.91 to 1.03) | 5.10 (4.86 to 5.36) |
| RSV-B: Day 181 | 0.83 (0.77 to 0.89) | 1.98 (1.89 to 2.08) |
| RSV-B: Day 365 | 0.80 (0.73 to 0.88) | 1.41 (1.35 to 1.48) |
| RSV-B: Day 730 | 0.86 (0.76 to 0.97) | 1.32 (1.26 to 1.39) |
A ≥2-fold increase from baseline was defined as a change from below the LLOQ to equal or above 2 \* LLOQ, or at least a 2-fold increase if baseline was equal to or above the LLOQ. Part A PPI Set: a randomly selected subset of participants who: a) received the assigned study drug, b) had RSV immunogenicity titer results at baseline (prior to study drug administration) and at least 1 valid result after the study drug administration at timepoint of interest, and c) had no major protocol deviation affecting the primary immunogenicity outcomes as determined prior to database lock and unblinding.
| percentage of participants | Part A: Placebo | Part A: mRNA-1345 |
|---|---|---|
| RSV-A: Day 29 | 4.5 (2.6 to 7.3) | 91.1 (89.6 to 92.5) |
| RSV-A: Day 181 | 7.9 (5.2 to 11.5) | 60.9 (58.3 to 63.4) |
| RSV-A: Day 365 | 10.5 (7.3 to 14.4) | 42.7 (40.0 to 45.4) |
| RSV-A: Day 730 | 13.5 (9.7 to 18.1) | 35.2 (32.5 to 38.0) |
| RSV-B: Day 29 | 5.4 (3.2 to 8.4) | 84.2 (82.2 to 86.0) |
| RSV-B: Day 181 | 8.9 (6.0 to 12.6) | 46.7 (44.0 to 49.3) |
| RSV-B: Day 365 | 9.2 (6.2 to 13.0) | 29.6 (27.1 to 32.1) |
| RSV-B: Day 730 | 15.7 (11.6 to 20.6) | 27.6 (25.1 to 30.2) |
Seroresponse was defined as a post-primary dose or post-revaccination titer ≥4 \* LLOQ if Baseline was \<LLOQ or a ≥4-fold increase from baseline if baseline was ≥LLOQ. Part B PP Set: all Part B randomized participants who received both Parts A and B assigned study intervention doses, had RSV immunogenicity titer results at pre-Primary Dose (baseline), had RSV immunogenicity titer results at Primary Dose Day 29, had at least 1 valid result at Revaccination Day 29, and had no major protocol deviations affecting the primary immunogenicity outcomes as determined prior to database lock and unblinding. Participants were analyzed according to the study intervention group to which they were randomized.
| percentage of participants | mRNA-1345 Primary Vaccination | mRNA-1345 Revaccination |
|---|---|---|
| RSV-A | 73.3 (70.4 to 76.1) | 66.0 (62.9 to 69.0) |
| RSV-B | 57.9 (54.7 to 61.1) | 46.0 (42.8 to 49.2) |
Antibody values reported as below LLOQ replaced by 0.5 \* LLOQ. Values greater than ULOQ replaced by ULOQ. LLOQ = 13 IU/mL, ULOQ = 259061 IU/mL for RSV-A nAb. LLOQ = 10, ULOQ = 112476 for RSV-B nAb. Part B PP Set: all Part B randomized participants who received both Parts A and B assigned study intervention doses, had RSV immunogenicity titer results at pre-Primary Dose (baseline), had RSV immunogenicity titer results at Primary Dose Day 29, had at least 1 valid result at Revaccination Day 29, and had no major protocol deviations affecting the primary immunogenicity outcomes as determined prior to database lock and unblinding. Participants were analyzed according to the study intervention group to which they were randomized.
| IU/mL | Part B: Placebo | Part B: mRNA-1345 |
|---|---|---|
| RSV-A: BD Day 1 | 3533.60 (3212.07 to 3887.31) | 4186.08 (3899.52 to 4493.69) |
| RSV-A: BD Day 181 | 3156.10 (2846.53 to 3499.35) | 6256.67 (5818.27 to 6728.10) |
| RSV-B: BD Day 1 | 1636.66 (1504.60 to 1780.31) | 1626.56 (1529.35 to 1729.95) |
| RSV-B: BD Day 181 | 1495.45 (1366.74 to 1636.27) | 2269.18 (2133.63 to 2413.34) |
Antibody values reported as below LLOQ replaced by 0.5 \* LLOQ. Values greater than ULOQ replaced by ULOQ. LLOQ = 13 IU/mL, ULOQ = 259061 IU/mL for RSV-A nAb. LLOQ = 10, ULOQ = 112476 for RSV-B nAb. Part B PP Set: all Part B randomized participants who received both Parts A and B assigned study intervention doses, had RSV immunogenicity titer results at pre-Primary Dose (baseline), had RSV immunogenicity titer results at Primary Dose Day 29, had at least 1 valid result at Revaccination Day 29, and had no major protocol deviations affecting the primary immunogenicity outcomes as determined prior to database lock and unblinding. Participants were analyzed according to the study intervention group to which they were randomized.
| ratio | Part B: Placebo | Part B: mRNA-1345 |
|---|---|---|
| RSV-A: BD Day 1 | 1.73 (1.58 to 1.88) | 2.04 (1.91 to 2.18) |
| RSV-A: BD Day 29 | 1.74 (1.59 to 1.91) | 6.01 (5.57 to 6.50) |
| RSV-A: BD Day 181 | 1.58 (1.44 to 1.73) | 3.05 (2.84 to 3.27) |
| RSV-B: BD Day 1 | 1.31 (1.22 to 1.41) | 1.46 (1.38 to 1.54) |
| RSV-B: BD Day 29 | 1.24 (1.16 to 1.33) | 3.59 (3.36 to 3.84) |
| RSV-B: BD Day 181 | 1.22 (1.13 to 1.31) | 2.02 (1.90 to 2.15) |
Seroresponse was defined as a post-primary dose or post-revaccination titer ≥4 \* LLOQ if Baseline was \<LLOQ or a ≥4-fold increase from baseline if baseline was ≥LLOQ. Part B PP Set: all Part B randomized participants who received both Parts A and B assigned study intervention doses, had RSV immunogenicity titer results at pre-Primary Dose (baseline), had RSV immunogenicity titer results at Primary Dose Day 29, had at least 1 valid result at Revaccination Day 29, and had no major protocol deviations affecting the primary immunogenicity outcomes as determined prior to database lock and unblinding. Participants were analyzed according to the study intervention group to which they were randomized.
| percentage of participants | Part B: Placebo | Part B: mRNA-1345 |
|---|---|---|
| RSV-A: BD Day 1 | 18.8 (15.5 to 22.6) | 22.6 (20.0 to 25.4) |
| RSV-A: BD Day 29 | 18.2 (14.9 to 22.0) | 66.0 (62.9 to 69.0) |
| RSV-A: BD Day 181 | 15.7 (12.5 to 19.3) | 39.4 (36.2 to 42.6) |
| RSV-B: BD Day 1 | 6.7 (4.7 to 9.4) | 9.6 (7.8 to 11.7) |
| RSV-B: BD Day 29 | 6.7 (4.7 to 9.4) | 46.0 (42.8 to 49.2) |
| RSV-B: BD Day 181 | 7.5 (5.3 to 10.3) | 20.3 (17.7 to 23.1) |
Collected over All-cause mortality, SAEs, AESIs, MAAEs, and AEs led to study discontinuation: up to Month 24 (Part A) and up to BD Day 181 (Part B). Non-serious AEs: up to 28 days after study injection, unless they met criteria for AESIs, MAAEs, or AEs led to study discontinuation.. Non-serious events are listed at a 5% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Part A: Placebo | 307/18,387 (1.7%) | 2,745/18,316 (15%) | 6,916/18,316 (37.8%) |
| Part A: mRNA-1345 | 301/18,427 (1.6%) | 2,773/18,369 (15.1%) | 7,080/18,369 (38.5%) |
| Part B: Placebo | 1/505 (0.2%) | 26/504 (5.2%) | 29/504 (5.8%) |
| Part B: mRNA-1345 | 0/1,005 (0%) | 29/998 (2.9%) | 48/998 (4.8%) |
| Event | Part A: Placebo | Part A: mRNA-1345 | Part B: Placebo | Part B: mRNA-1345 |
|---|---|---|---|---|
| PneumoniaInfections and infestations | 147/18316 | 163/18369 | 2/504 | 3/998 |
| OsteoarthritisMusculoskeletal and connective tissue disorders | 108/18316 | 114/18369 | 4/504 | 2/998 |
| Chronic obstructive pulmonary diseaseRespiratory, thoracic and mediastinal disorders | 94/18316 | 111/18369 | 0/504 | 0/998 |
| Acute myocardial infarctionCardiac disorders | 73/18316 | 85/18369 | 0/504 | 0/998 |
| Atrial fibrillationCardiac disorders | 83/18316 | 80/18369 | 0/504 | 0/998 |
| Urinary tract infectionInfections and infestations | 76/18316 | 66/18369 | 0/504 | 0/998 |
| HyponatraemiaMetabolism and nutrition disorders | 7/18316 | 16/18369 | 2/504 | 0/998 |
| Cardiac arrestCardiac disorders | 66/18316 | 58/18369 | 0/504 | 1/998 |
| Coronary artery diseaseCardiac disorders | 62/18316 | 60/18369 | 0/504 | 1/998 |
| Prostate cancerNeoplasms benign, malignant and unspecified (incl cysts and polyps) | 56/18316 | 52/18369 | 0/504 | 0/998 |
| Event | Part A: Placebo | Part A: mRNA-1345 | Part B: Placebo | Part B: mRNA-1345 |
|---|---|---|---|---|
| COVID-19Infections and infestations | 3302/18316 | 3404/18369 | 14/504 | 22/998 |
| Upper respiratory tract infectionInfections and infestations | 2153/18316 | 2198/18369 | 13/504 | 17/998 |
| Rhinovirus infectionInfections and infestations | 1683/18316 | 1698/18369 | 3/504 | 2/998 |
| NasopharyngitisInfections and infestations | 1384/18316 | 1430/18369 | 0/504 | 0/998 |
| HypertensionVascular disorders | 1225/18316 | 1244/18369 | 2/504 | 8/998 |
Randomization Set included all participants who were randomized in the study, regardless of the participant's study intervention administration status. Participants were included in the vaccination group to which they were randomized.
| Age, Continuous(years) | Placebo | mRNA-1345 | Total |
|---|---|---|---|
| Mean | 68.5 ± 6.61 | 68.5 ± 6.59 | 68.5 ± 6.60 |
| Sex: Female, Male(Participants) | Placebo | mRNA-1345 | Total |
|---|---|---|---|
| Female | 9057 | 9017 | 18074 |
| Male | 9330 | 9410 | 18740 |
| Ethnicity (NIH/OMB)(Participants) | Placebo | mRNA-1345 | Total |
|---|---|---|---|
| Hispanic or Latino | 6168 | 6117 | 12285 |
| Not Hispanic or Latino | 12010 | 12124 | 24134 |
| Unknown or Not Reported | 209 | 186 | 395 |
| Race/Ethnicity, Customized(Participants) | Placebo | mRNA-1345 | Total |
|---|---|---|---|
| Race — White | 11290 | 11311 | 22601 |
| Race — Black or African American | 2173 | 2204 | 4377 |
| Race — Asian | 2138 | 2151 | 4289 |
| Race — American Indian or Alaska Native | 896 | 906 | 1802 |
| Race — Native Hawaiian or Other Pacific Islander | 19 | 28 | 47 |
| Race — Other | 1013 | 996 | 2009 |
| Race — Multiple | 752 | 762 | 1514 |
| Race — Unknown | 20 | 10 | 30 |
| Race — Not Reported | 86 | 59 | 145 |
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