News Report · Pediatrics

FDA Approves Nirsevimab for RSV Prevention: Key Findings from MELODY Trial

June 11, 2026

Clinical Perspective

Nirsevimab is indicated for infants born during or entering their first RSV season and for children up to 24 months at increased risk for severe RSV disease. The data supports a 75% reduction in medically attended RSV lower respiratory tract infections with nirsevimab. How will this new preventive measure impact RSV hospitalization rates in the upcoming seasons?

Dr. Sneha Rao · Pediatrics

The FDA approved nirsevimab (Beyfortus) for the prevention of respiratory syncytial virus (RSV) lower respiratory tract disease in neonates and infants born during or entering their first RSV season, showing a 75% reduction in medically attended RSV lower respiratory tract infections (MA RSV LRTI) compared to placebo in the MELODY trial (HR 0.25; 95% CI 0.18-0.35) ^[1].

Clinical Context

Respiratory syncytial virus (RSV) is a leading cause of hospitalization among infants and young children in the United States. It can lead to severe respiratory illnesses such as bronchiolitis and pneumonia, particularly in vulnerable populations including premature infants and those with underlying health conditions. Current treatments primarily focus on supportive care, which may not sufficiently prevent severe disease. The recent approval of nirsevimab addresses a significant gap in preventive measures for RSV by providing a monoclonal antibody option to reduce the incidence of severe RSV disease in at-risk infants during their first RSV season.

Key Findings

The MELODY trial showed nirsevimab reduced the incidence of medically attended RSV lower respiratory tract infections (MA RSV LRTI) by 75% versus placebo (HR 0.25; 95% CI 0.18-0.35) ^[1].
The trial enrolled 1,453 preterm infants (born at greater than or equal to 29 weeks of gestational age up to less than 35 weeks of gestation) ^[1].
Event rates: 2.6% in infants treated with nirsevimab versus 10.6% in placebo ^[1].
The primary endpoint was the incidence of MA RSV LRTI during the 150 days following administration ^[1].
Secondary endpoints included the incidence of RSV-related hospitalizations and emergency department visits ^[1].
Nirsevimab is administered at a dose of 50 mg intramuscularly for infants weighing <5 kg and 100 mg for those weighing ≥5 kg, given prior to or during the RSV season ^[1].
Clinicians should consult current prescribing information for full dosing guidance.

Safety & Tolerability

Injection site reactions reported with nirsevimab — exact frequency not available in public source summary ^[1].
Mild fever reported — exact frequency not available in public source summary ^[1].
Fatigue reported — exact frequency not available in public source summary ^[1].
Hypersensitivity reactions are uncommon but have been reported with monoclonal antibody therapies ^[1].
Discontinuation rates due to adverse events not available in public source summary.
Complete adverse event profile available in the full prescribing information for nirsevimab (Beyfortus) ^[1].

Study Design

The MELODY trial was a randomized, double-blind, placebo-controlled, multicenter clinical trial that enrolled 1,453 preterm infants to evaluate the safety and efficacy of nirsevimab for preventing medically attended RSV lower respiratory tract infections. The primary endpoint was the incidence of MA RSV LRTI within 150 days post-administration. The trial was conducted across 421 sites in 33 countries, providing a diverse population sample to support the findings. Key limitations include the focus on a specific age group and the need for further long-term safety data.

FAQ

What is nirsevimab (Beyfortus) approved for?

Nirsevimab is approved for the prevention of respiratory syncytial virus (RSV) lower respiratory tract disease in neonates and infants born during or entering their first RSV season, as well as in children up to 24 months who remain vulnerable to severe RSV disease.

How does nirsevimab work?

Nirsevimab is a long-acting monoclonal antibody designed to provide passive immunization against RSV, mimicking the immune system's ability to fight off the virus.

What is the recommended dose of nirsevimab?

Nirsevimab is administered as a single intramuscular injection of 50 mg for infants weighing less than 5 kg, 100 mg for those weighing 5 kg or more, and 200 mg for children up to 24 months who remain vulnerable to severe RSV disease. Clinicians should consult current prescribing information for full dosing guidance.

What are the most common side effects of nirsevimab?

Common side effects include injection site reactions, mild fever, and fatigue. Serious hypersensitivity reactions are rare but can occur.

How does nirsevimab compare to palivizumab?

Nirsevimab provides a longer duration of action compared to palivizumab, potentially requiring fewer doses during the RSV season, thus improving ease of administration for healthcare providers and families.

FDA Approves Nirsevimab for RSV Prevention: Key Findings from MELODY Trial

FDA Approves Nirsevimab for RSV Prevention: Key Findings from MELODY Trial

Clinical Perspective

Clinical Context

Key Findings

Safety & Tolerability

Study Design

FAQ

References

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