In an effort to greater prepare HCPs and to avoid potential shortages, the company targets Q3 as the shipment date.
Beginning in early Q3, Sanofi will be shipping Beyfortus (nirsevimab) in order to make sure that there is plenty of availability heading into the 2025-2026 respiratory syncytial virus (RSV) season.1 The season itself normally runs in November through March.
Beyfortus is a monoclonal antibody designed to protect newborns and infants under 8 months old from RSV-related lower respiratory tract disease during their first RSV season. Vaccines to treat RSV normally start in early fall, and having these additional shipments in advance is expected to give healthcare providers (HCPs) an additional assurance and confidence.
AstraZeneca has been working hand-in-hand with Sanofi on the production front since its launch in 2023. Over the past couple years, the demand for this RSV vaccine has continued to be high; in fact, Sanofi had announced in October 2023 that the extraordinary demand had caused shortages impacting the 2023-2024 season.2
As a result, the Centers for Disease Control and Prevention (CDC) issued recommendations to address the shortage, advising that available 100 mg doses of Beyfortus be prioritized for infants under 6 months old, along with those with underlying conditions that raise their risk of severe RSV disease.2 The CDC did not revise any recommendations for the 50 mg doses at that time.
Now, the Sanofi-AstraZeneca partnership has resulted in tripled production capacity, along with twice the number of manufacturing facilities. As of now, supply for this coming season matches last year’s total dosage, with production expected to continue.
“Our third year of providing RSV protection marks a transformative era in infant health. Backed by more than 40 real-world studies involving 250,000 immunized infants, Beyfortus has consistently proven itself as an effective RSV immunization,” said Thomas Triomphe, Sanofi’se xecutive vice president of vaccines.“To meet growing demand since launch, we have meticulously primed our global distribution network to ensure Beyfortus will continue to deliver significant public health impact and offer high, sustained efficacy for infants regardless of underlying health conditions or the timing of when they are born.”
As alluded to by Triomphe, there have a plethora of studies proving Beyforthus’ efficacy. For instance, an immunization program that was executed in Spain using Beyfortus reportedly reduced infant hospitalizations due to RSV by 69.0% during the 2024-2025 RSV season compared to the 2022-2023 season, per data presented at the 43rd Annual Meeting of the European Society for Pediatric Infectious Diseases (ESPID).3 This real-world analysis also suggested that a program in the UK using only the RSVpreF maternal vaccine reduced infant RSV hospitalizations in infants by 26.7% over those aforementioned RSV seasons.
According to Sanofi, this observational, retrospective REACH study is considered the first public health impact analysis of infant RSV prevention programs that features multiple countries.
Also at ESPID, durability data from the HARMONIE Phase 3b clinical study was shared.3 Now published in The Lancet Child & Adolescent Health, it essentially concluded Beyfortus reduced RSV hospitalizations in infants by 82.7% (95% CI: 67.8 to 91.5; p<0.0001) through six months (180 days) compared to no intervention, surpassing the standard length of the five-month RSV season.
Primary analysis also showed that there was a higher efficacy of 83.2% previously, which continued over the longer follow-up period without any proof of diminishing protection in infants born before or during the RSV season.3
References
1. Press Release: Sanofi accelerates global shipping of Beyfortus to prepare healthcare providers months ahead of 2025-2026 RSV season. Sanofi. June 9, 2025. Accessed June 9, 2025.
2. James D. Sanofi, AstraZeneca Launch Program to Mitigate Future RSV Vaccine Shortages. Sanofi. February 2, 2024. Accessed June 9, 2025.
3. Beyfortus public health advantage bolstered by first real-world comparison of infant vs maternal RSV immunization programs. Sanofi. May 25, 2025. Accessed June 9, 2025.
