TOPLINE:

mRNA-1345, a lipid nanoparticle encapsulated messenger RNA (mRNA)-based vaccine, was well tolerated and immunogenic in solid organ transplant recipients, inducing neutralizing antibodies against respiratory syncytial virus (RSV)-A and RSV-B after a single dose, with modest further increases after a second dose.

METHODOLOGY:

• In this ongoing phase 3 study, researchers assessed the clinical profile of mRNA-1345 in recipients of a kidney, liver, or lung transplant ≥ 180 days before enrollment and who were receiving immunosuppressive therapy.
• They included 150 recipients (mean age, 55.1 years; 62.7% male) with a solid organ transplant between October 2023 and July 2024 across 22 centers in the US, Canada, and the UK.
• All recipients received the first dose of mRNA-1345 (50 μg) intramuscularly on day 1, while 146 recipients received the second dose on day 57.
• The primary objectives were safety, tolerability, and immunogenicity measured by neutralizing antibody levels against RSV-A and RSV-B on day 85, while secondary objectives included assessment of antibody levels on days 29 and 181 and the fold increase from baseline.
• Medically attended adverse events (AEs) were defined as AEs leading to an unscheduled visit to a healthcare provider.

TAKEAWAY:

• The unsolicited AEs and medically attended AEs occurred in 34.0% and 24.7% of recipients, respectively, after any dose. One grade 4 arthralgia occurred after dose 2, and no vaccine-related discontinuations, deaths, or AEs of special interest were reported within 28 days.
• By day 29, a single dose of mRNA-1345 induced immunogenic responses across all transplant recipients, with antibody levels increasing to 9381.18 IU/mL for RSV-A (4.9-fold increase; 95% CI, 3.87-6.25) and 2838.18 IU/mL for RSV-B (3.4-fold increase; 95% CI, 2.82-4.05) from baseline.
• At day 85, antibody response increased further after the second dose, reaching 7.1-fold (95% CI, 5.67-8.80) for RSV-A and 5.2-fold (95% CI, 4.34-6.17) for RSV-B, and remained above baseline through day 181.
• Cellular immune responses increased after dose 1, increased further after dose 2, and remained elevated through day 181.

IN PRACTICE:

“[Our] findings suggest that mRNA-1345 may be a valuable preventive tool against RSV in immunocompromised adults,” the authors of the study wrote.

SOURCE:

The study was led by Erick F. Mayer, MD, Moderna, Inc., Cambridge, Massachusetts. It was published online on February 18, 2026, in Clinical Infectious Diseases.

LIMITATIONS:

The study was limited by the absence of a control group or single-dose comparator and by the descriptive nature of all immunogenicity endpoints. Additionally, no formal efficacy evaluation was performed, and follow-up was limited.

DISCLOSURES:

The study was supported by Moderna, Inc. Seven authors reported being employees and maybe holding stock/stock options of the supporter company. Some authors reported receiving research funding, honoraria, and consultancy fees and being advisory board members for various pharmaceutical companies.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.