A Phase 3, Randomized, Observer-Blind Study to Evaluate Safety, Tolerability, and Immunogenicity of mRNA-1345, an mRNA Vaccine Targeting Respiratory Syncytial Virus, When Coadministered With a High-Dose, Quadrivalent Seasonal Influenza Vaccine in Adults ≥65 Years of Age

Number of Participants With Unsolicited Adverse Events (AEs) Up to 21 Days After Day 1 Injection

时间窗: Up to 21 days after Day 1 injection

An AE was defined as any untoward medical occurrence associated with the use of a drug in humans, whether or not considered drug related. Any abnormal laboratory test result (hematology, clinical chemistry, or prothrombin time \[PT\]/partial thromboplastin time \[PTT\]) or other safety assessment (for example, electrocardiogram, radiological scan, vital sign measurement), including one that worsened from baseline and was considered clinically significant in the medical and scientific judgment of the Investigator was recorded as an AE. A summary of SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the "Reported Adverse Events" section.

Number of Participants With Unsolicited AEs Up to 21 Days After Day 22 Injection

时间窗: Up to 21 days after Day 22 injection

An AE was defined as any untoward medical occurrence associated with the use of a drug in humans, whether or not considered drug related. Any abnormal laboratory test result (hematology, clinical chemistry, or PT/PTT) or other safety assessment (for example, electrocardiogram, radiological scan, vital sign measurement), including one that worsened from baseline and was considered clinically significant in the medical and scientific judgment of the Investigator was recorded as an AE. A summary of SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the "Reported Adverse Events" section.

Geometric Mean Titer (GMT) of Serum Respiratory Syncytial Virus Subtype A (RSV-A) and Respiratory Syncytial Virus Subtype B (RSV-B) Neutralizing Antibodies (nAbs)

时间窗: Day 22 (for Arm 1) and Day 43 (for Arm 2)

Antibody values reported as below lower limit of quantification (LLOQ) were replaced by 0.5\*LLOQ. Values greater than the upper limit of quantification (ULOQ) were replaced by the ULOQ. LLOQ was 13 international units (IU)/milliliter (mL) and ULOQ was 259061 IU/mL for RSV-A. LLOQ was 10 IU/mL and ULOQ was 112476 for RSV-B.

GMT of Serum Anti-Hemagglutination (HA) Ab Level, as Measured by Hemagglutination Inhibition (HAI) Assay

时间窗: Day 22

Influenza A strains included H1N1 and H3N2 and influenza B strains included Austria and Phuket strains. Antibody values reported as below LLOQ were replaced by 0.5\*LLOQ. Values greater than the ULOQ were replaced by the ULOQ. LLOQ was 10 and ULOQ was 2560 for Influenza A. LLOQ was 10 and ULOQ was 640 for Influenza B.

Number of Participants With Solicited Local and Systemic Adverse Reactions (ARs) Within 7 Days After Day 1 Injection

时间窗: Within 7 days after Day 1 injection

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.

Number of Participants With Solicited Local and Systemic ARs Within 7 Days After Day 22 Injection

时间窗: Within 7 days after Day 22 injection

Solicited ARs were collected in an 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 AEs. Investigator reviewed whether the solicited AR was also to be recorded as an AE. A Summary of SAEs and nonserious AEs ("Other"), regardless of causality, is located in the "Reported Adverse Events" section.

Number of Participants With Medically Attended Adverse Events (MAAEs), Adverse Events of Special Interest (AESIs), Serious Adverse Events (SAEs), and AEs Leading to Discontinuation

时间窗: Day 1 through Day 202

A MAAE is an AE that leads to an unscheduled visit to a healthcare practitioner. An AESI is an AE (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 are required. An SAE was defined as any AE that resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in disability, was a congenital anomaly/birth defect, or was an important medical event. A summary of SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the "Reported Adverse Events" section.