Press Release: Beyfortus real-world evidence published in The Lancet shows 82% reduction in infant RSV hospitalizations

Beyfortus reduced respiratory syncytial virus hospitalizations by 82% in infants under 6 months of age, compared to infants who received no RSV intervention, according to the interim results of an ongoing study published in The Lancet.

Beyfortus real-world evidence published in The Lancet shows 82% reduction in infant RSV hospitalizations

  • New real-world evidence shows Beyfortus (nirsevimab) substantially reduced RSV lower respiratory tract disease and hospitalizations in infants during the 2023-2024 RSV season, versus no intervention1-6
  • Results add to the consistent high efficacy of Beyfortus against medically attended RSV lower respiratory tract disease, shown in the pivotal clinical studies and the outcomes from HARMONIE, a phase 3b clinical study conducted in close to real-life conditions7-10

Paris, May 2, 2024. Beyfortus reduced respiratory syncytial virus (RSV) hospitalizations by 82% (95% CI: 65.6 to 90.2) in infants under 6 months of age, compared to infants who received no RSV intervention, according to the interim results of an ongoing study published in The Lancet. These results, from the first RSV season after Beyfortus’ introduction, are part of the three-year NIRSE-GAL study conducted in Galicia, Spain under a collaborative framework with the Galician Directorate of Public Health of the Xunta de Galicia (Galician government) and Sanofi.1

The results echo real-world evidence (RWE) reported from several broad infant immunization programs across the US, Spain and France during the 2023-2024 RSV season, which add to the consistent and high efficacy seen in pivotal clinical studies with Beyfortus. Real-world evidence demonstrates if a treatment or immunization is effective in day-to-day practice, as opposed to “efficacy” determined in carefully controlled clinical trials. A favorable safety profile was observed following Beyfortus use, consistent with clinical study results.1-10

Federico Martinon Torres
Head of Pediatrics, Hospital Clínico Universitario Santiago, Spain and principal investigator of NIRSE-GAL study
“Galicia provides the first population-based real-world evidence of the impact of nirsevimab to prevent RSV disease in infants, showing a reduction by almost 90% in the number of hospitalizations due to this virus when compared with several previous RSV seasons. This achievement is the result of the exemplary pragmatic collaboration among scientists, industry, healthcare providers and policy makers aligned with a carefully planned roll-out of the immunization campaign, and the outstanding response of the Galician parents to this prophylaxis campaign.”

Thomas Triomphe
Executive Vice President, Vaccines, Sanofi
“The scale and speed of impact seen after Beyfortus’ introduction demonstrates the strength of all-infant immunization strategies against RSV in babies. In Galicia, we saw an effectiveness of 82% in reducing RSV hospitalizations following the launch of Beyfortus, with more than 90% of eligible infants immunized. A growing body of evidence from these programs support policymakers, healthcare providers and parents who share our collective ambition to safeguard babies from RSV disease.”

NIRSE-GAL is a large, population-based, three-year follow-up study to evaluate the effectiveness of Beyfortus following its inclusion in the Galician immunization schedule. The study aims to measure the impact of Beyfortus on hospitalizations due to RSV, all-cause lower respiratory tract disease, severe lower respiratory tract disease caused by RSV, all-cause lower respiratory tract disease hospitalizations, and all-cause hospitalizations among infants born during the RSV season, infants under 6 months of age at the start of the season, and children aged 6-24 months who are vulnerable to severe RSV disease at the start of the season. The 2023-2024 immunization campaign ran from September 25, 2023 to March 31, 2024.1

RWE from countries with Beyfortus all-infant immunization programs in 2023-24

In addition to this new effectiveness study, evidence of the high impact following Beyfortus’ introduction has been consistently shown in several other real-world studies.

  • An interim analysis of 2023-24 surveillance data published in the US Centers for Disease Control and Prevention’s (CDC) Morbidity and Mortality Weekly Report (MMWR) shows a single dose of Beyfortus was 90% effective in preventing hospitalizations due to RSV in babies who were immunized below 8 months of age.2
  • A recent draft recommendation from Haute Autorité de Santé in France reported, across six hospitals, an effectiveness of 83% against RSV-associated hospitalization in infants who received Beyfortus compared to those with no intervention.3
  • In Catalonia, Spain, a study pre-printed in The Lancet showed reductions of 87.6% and 90.1% in hospital and ICU admissions for RSV, respectively, among babies born before the start of the RSV season, who were eligible to receive Beyfortus, compared to those with no intervention.4
  • A pooled analysis of data from three Spanish regions, including Valencia, Murcia, and Valladolid, showed an 84.4% effectiveness in preventing hospitalizations due to RSV in infants under 9 months of age versus infants who received no intervention. The results were published in Eurosurveillance.5
  • A study from Navarra, Spain published in Vaccines found an effectiveness of 88.7% in preventing hospitalizations among infants immunized at birth with Beyfortus, compared to no intervention.6

The expansion of the Beyfortus manufacturing network is progressing well and according to plan. This expansion will allow Sanofi and AstraZeneca to more than triple manufacturing capacity. Based on this, and assuming regulatory validations are delivered in due time by regulatory agencies, Sanofi and AstraZeneca are confident to meet global commitments and build inventory that can be used in future RSV seasons. In addition, the companies are producing Beyfortus well in advance of the RSV season, with the vast majority of doses planned to be available by October.

About RSV
RSV is a highly contagious virus that can lead to serious respiratory illness for infants.11 Two out of three infants are infected with RSV during their first year of life and almost all children are infected by their second birthday.11,12 RSV is the most common cause of lower respiratory tract disease, including bronchiolitis and pneumonia, in infants.13 It is also a leading cause of hospitalization in infants worldwide, with most hospitalizations for RSV occurring in healthy infants born at term.14-17 Globally, in 2019, there were approximately 33 million cases of acute lower respiratory infections leading to more than 3 million hospitalizations, and it was estimated that there were 26,300 in-hospital deaths of children younger than 5 years.18 RSV-related direct medical costs, globally — including hospital, outpatient and follow-up care — were estimated at €4.82 billion in 2017.19

About Beyfortus
Beyfortus (nirsevimab) is the first immunization designed for all infants for protection against RSV through their first RSV season, including for those born healthy at term or preterm, or with specific health conditions that make them vulnerable to RSV disease. Beyfortus is also designed to protect children up to 24 months of age who remain vulnerable to severe RSV disease through their second RSV season.

As a long-acting antibody provided directly to newborns and infants as a single dose, Beyfortus offers rapid protection to help prevent lower respiratory tract disease caused by RSV without requiring activation of the immune system. Beyfortus administration can be timed to coincide with the RSV season.

In March 2017, Sanofi and AstraZeneca announced an agreement to develop and commercialize Beyfortus. Under the terms of the agreement, AstraZeneca leads development and manufacturing activities and Sanofi leads commercialization activities and records revenues. Under the terms of the global agreement, Sanofi made an upfront payment of €120m, has paid development and regulatory milestones of €120m and will pay up to a further €375m upon achievement of certain regulatory and sales-related milestones. The two companies share costs and profits in all territories except in the US where Sanofi consolidates 100% of the economic benefits in its Business Operating Income.

Beyfortus has been approved for use in the European Union, the US, China, Japan, and many other countries around the world. Special designations to facilitate expedited development of Beyfortus were granted by several regulatory agencies, including Breakthrough Therapy Designation and Priority Review designation by The China Center for Drug Evaluation under the National Medical Products Administration; Breakthrough Therapy Designation and Fast Track Designation from the US Food and Drug Administration; access granted to the European Medicines Agency (EMA) PRIority MEdicines (PRIME) scheme and EMA accelerated assessment; Promising Innovative Medicine designation by the UK Medicines and Healthcare products Regulatory Agency; and Beyfortus has been named “a medicine for prioritized development” under the Project for Drug Selection to Promote New Drug Development in Pediatrics by the Japan Agency for Medical Research and Development.

About Sanofi
We are an innovative global healthcare company, driven by one purpose: we chase the miracles of science to improve people’s lives. Our team, across the world, is dedicated to transforming the practice of medicine by working to turn the impossible into the possible. We provide potentially life-changing treatment options and life-saving vaccine protection to millions of people globally, while putting sustainability and social responsibility at the center of our ambitions.
Sanofi is listed on EURONEXT: SAN and NASDAQ: SNY

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  2. U.S. Centers for Disease Control and Prevention. Early Estimate of Nirsevimab Effectiveness for Prevention of Respiratory Syncytial Virus–Associated Hospitalization Among Infants Entering Their First Respiratory Syncytial Virus Season — New Vaccine Surveillance Network, October 2023–February 2024. Morbidity and Mortality Weekly Report (MMWR). 2024; 73(9);209–214.
  3. Haute Autorité de santé. Recommandation vaccinale contre les infections à VRS chez les femmes enceintes. April 25, 2024.
  4. Coma E, et al. Effectiveness of Nirsevimab Immunoprophylaxis Against Respiratory Syncytial Virus-Related Outcomes in Hospital and Primary Care Settings: A Retrospective Cohort Study in Infants in Catalonia (Spain). Preprints with The Lancet. March 7, 2024.
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