French healthcare company Sanofi S.A. (Euronext Paris:SAN) (Nasdaq:SNY) said on Monday that it is planning to start shipping Beyfortus (nirsevimab) early in the third quarter to ensure widespread availability ahead of the 2025-2026 respiratory syncytial virus (RSV) season.

This proactive distribution aims to help healthcare providers prepare in advance of immunisations, which typically begin in early autumn.

Sanofi, in collaboration with its partner AstraZeneca (NASDAQ:AZN), has tripled production capacity and doubled the number of manufacturing sites since Beyfortus launched in 2023. Supply for the upcoming RSV season already matches last year's total distribution, which covered all infants in the United States.

Beyfortus remains the only RSV immunisation designed to protect all infants -- regardless of health status or gestational age -- with a single dose offering high, sustained efficacy throughout the season. In the European Union, the product's label now reflects extended protection lasting six months, aligning with season-long needs for older infants immunised later in the year.

More than six million infants have already received Beyfortus across over 40 countries, with millions more expected this season. RSV continues to be a major cause of infant hospitalisation worldwide, predominantly affecting otherwise healthy, full-term babies.

With a 71-day half-life, Beyfortus is the longest-acting monoclonal antibody for RSV prevention and is approved for use through a child's second RSV season. It provides immediate, passive immunity without requiring immune system activation.

Beyfortus has received regulatory approvals and accelerated designations in key markets including the United States, European Union, Japan and China.