CDC and AAP issue RSV season guidance: nirsevimab (Beyfortus) dosing and supply allocation for 2026–27
CDC and the American Academy of Pediatrics issued updated guidance for the 2026–27 RSV season recommending nirsevimab (Beyfortus; AstraZeneca/Sanofi) as first-line prophylaxis for all infants under 8 months entering their first RSV season, and for high-risk infants aged 8–19 months. The guidance clarifies weight-based dosing (50 mg for <5 kg, 100 mg for ≥5 kg) and palivizumab (Synagis) as an alternative when nirsevimab is unavailable.
On 8 October 2026, the CDC MMWR ↗ and the American Academy of Pediatrics (AAP) ↗ issued updated dosing and supply allocation guidance for nirsevimab (Beyfortus, Sanofi/AstraZeneca ↗) for the 2026–27 RSV season. The guidance prioritises infants most at risk during anticipated supply constraints and reiterates the two-dose weight-band regimen.
About nirsevimab and RSV prevention
Respiratory syncytial virus (RSV) ↗ is the leading cause of infant hospitalisation in the US, with approximately 58,000 hospitalisations annually in children under 5. Nirsevimab is a long-acting monoclonal antibody (half-life ~70 days) that binds the RSV fusion protein, preventing viral entry — unlike palivizumab (Synagis), which requires monthly injections during RSV season. A single dose of 50 mg (infants <5 kg) or 100 mg (infants ≥5 kg) provides season-long protection. The MELODY trial showed 74.5% efficacy against RSV-associated lower respiratory tract illness requiring medical attention.
2026–27 season allocation guidance
Given historical production constraints, CDC and AAP have defined a tiered priority framework: (1) newborns born October–March, hospitalised neonates before discharge; (2) high-risk infants under 6 months with CHD, CLD, immunocompromise, or Down syndrome; (3) all other infants entering their first RSV season under 8 months. Infants at highest risk of severe disease may also receive a second dose at the start of their second RSV season if aged 8–19 months with qualifying conditions. Healthcare providers should confirm current stock with wholesalers and enrol via the VFC programme ↗ for eligible patients.
Dosing and administration notes
Nirsevimab is administered as a single intramuscular injection (preferably anterolateral thigh) within 1 week of birth for neonates in RSV season, or before the start of RSV season for infants <8 months. It is not a vaccine and does not replace maternal RSV vaccination (Abrysvo). Concurrent administration with routine infant vaccines is permitted. For patients already receiving palivizumab, transition to nirsevimab is generally preferred due to single-dose convenience. See the updated ACIP RSV recommendations ↗ for the full recommendation table.
FAQ
Does a Boxed Warning mean a drug is being withdrawn?
No. A Boxed Warning ↗ (also called a Black Box Warning) is the FDA's strongest label caution, but the drug remains on the market. It means the agency has determined that a risk is serious enough to require prominent, standardised labelling. The drug continues to be prescribed under appropriate clinical conditions. See the FDA's patient guide to Boxed Warnings ↗.
Where can I read the full updated label?
All current FDA-approved prescribing information is available on DailyMed ↗, maintained by the National Library of Medicine (NLM). Search by drug name to find the most recent label version. Historical label versions are also archived there.