Beyfortus approved in China for the prevention of RSV disease in infants

AstraZeneca and Sanofi’s Beyfortus (nirsevimab), a long-acting monoclonal antibody, has been approved in China for the prevention of respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) in neonates and infants entering or during their first RSV season.1Beyfortus is anticipated to be available during the upcoming 2024-2025 RSV season.

Beyfortus is the first approved preventive option to protect against RSV in a broad infant population, including protecting those infants born healthy at term, or preterm, or with specific health conditions that make them vulnerable to severe RSV disease. The approval by The National Medical Products Administration (NMPA) is based on three Beyfortus pivotal late-stage clinical trials and an extensive local clinical development programme. Across all clinical endpoints, a single dose of Beyfortus demonstrated consistent efficacy against RSV lower respiratory tract disease (LRTD) extending through five months, the duration of a typical RSV season.2-5

RSV is a common and highly contagious seasonal virus. It is the most common cause of LRTD in infants, including bronchiolitis and pneumonia, and is also a leading cause of hospitalisation in all infants, with most hospitalisations for RSV occurring in healthy infants born at term.6 China ranks among countries with a high prevalence of RSV infections.7

Professor Liu Hanmin, President of West China Second University Hospital, Sichuan University, said: “There is currently no specific treatment for RSV disease in infants, and the potential long-term consequences of severe infections in infancy underscore the importance of prevention. As an innovative long-acting monoclonal antibody, Beyfortus can protect infants across the RSV season with a single dose. Its approval in China has the potential to alleviate the disease burden on children and their families and mitigate pressure on the medical system due to pediatric respiratory diseases. This approval represents a crucial contribution to the prevention and control of RSV disease in China.”

Iskra Reic, Executive Vice President, Vaccines and Immune Therapies, AstraZeneca, said: “Beyfortus represents the first opportunity to prevent serious respiratory disease due to RSV for all infants in China. The science that Beyfortus is built on demonstrates AstraZeneca’s leadership in addressing the needs of the most vulnerable populations and reducing the infectious disease burden on healthcare systems. We look forward to making Beyfortus available for the 2024/5 season.”

Beyfortus was approved in the European Union in October 2022 for the prevention of RSV LRTD in newborns and infants during their first RSV season and received approval by the US Food and Drug Administration in July 2023 following the unanimous recommendation by the Antimicrobial Drugs Advisory Committee in June 2023. Regulatory applications are also currently under review in Japan and several other countries.


Data from the Chinese Center for Disease Control and Prevention revealed that RSV is one of the leading viral pathogens causing acute respiratory infections in children under five years old, with infants under one year old experiencing the most substantial disease burden.6 Severe RSV infections in infants can lead to issues such as recurrent wheezing or asthma, indicative of impaired lung function, with potential long-term impact on the health of children.7 Data indicated that RSV ranks among the top three pathogens in children’s viral respiratory infections, potentially leading to a compounded epidemic of multiple respiratory viruses. This scenario places significant pressure on paediatricians, prompting increased medical treatment and hospitalisation. 8

Global pivotal clinical trials
The Phase IIb (Trial 03) study was a randomised, placebo-controlled trial designed to measure the efficacy of Beyfortus against medically attended (MA) Lower Respiratory Tract Infection (LRTI) through 150 days post-dose. Healthy preterm infants of 29 to less than 35 weeks’ gestational age were randomised (2:1) to receive a single 50mg intramuscular injection of Beyfortus or placebo regardless of weight.4,9

The Beyfortus dosing regimen was determined based on further exploration of the Phase IIb data and was used in subsequent trials as a single 50mg dose for those who weigh less than 5kg, or a single 100mg dose for those who weigh 5kg or greater.4,9

The MELODY Phase III study (Trial 04) was a randomised, double-blind, placebo-controlled trial conducted across 21 countries designed to determine efficacy of Beyfortus against medically attended LRTI through 150 days after dosing, versus placebo, in healthy term and late preterm infants (35 weeks gestational age or greater) entering their first RSV season.2,3,9

MEDLEY (Trial 05) was a Phase II/III, randomised, double-blind, Synagis (palivizumab)-controlled trial with the primary objective of assessing safety and tolerability for Beyfortus in preterm infants of less than 35 weeks gestational age and infants with congenital heart disease (CHD) and/or chronic lung disease of prematurity (CLD) eligible to receive Synagis. Between July 2019 and May 2021, a total of 925 infants entering their first RSV season were randomised to receive Beyfortus or Synagis. Safety was assessed by monitoring the occurrence of adverse events through 360 days post-dose. Serum levels of Beyfortus following dosing (on day 151) in this trial were comparable with those observed in the MELODY Phase III trial, indicating similar protection in this population to that in the healthy term and late preterm infants is likely. Data were published in the New England Journal of Medicine (NEJM) in March 2022.5,9

The safety profile of Beyfortus was similar to Synagis in the MEDLEY Phase II/III trial and consistent with the safety profile in healthy term and preterm infants studied in the MELODY and Phase IIb trials. While uncommon, the most reported adverse reactions were: rash 14 days post-dose, (the majority of which were mild to moderate); non-serious injection site reactions within 7 days post-dose.2,3,5,9

The results of MELODY, MEDLEY Phase II/III and the Phase IIb trials demonstrate that a single dose of Beyfortus helps protect infants during their first RSV season against RSV disease. This broad infant population includes healthy term, late preterm and preterm infants, as well as infants with specific health conditions that make them vulnerable to severe RSV disease.2-5,9

These trials formed the basis of regulatory submissions which began in 2022.

Results from the MELODY Phase III trial (Trial 04)
The primary endpoint of the MELODY Phase III trial was met, reducing the incidence of medically attended LRTI, such as bronchiolitis or pneumonia, caused by RSV by 74.9% (95% confidence interval (CI) 50.6, 87.3; P3 Observed events were 1.2% in treatment arm vs 5% in placebo arm. The efficacy of Beyfortus against the secondary endpoint of hospitalisation was 60.2% (95% CI: -14.6, 86.2). Observed events were 0.6% in treatment arm vs 1.6% in placebo arm. Between July 2019 and March 2020, 1,490 infants were randomised to receive either Beyfortus or placebo at the RSV season start. Initial data from the MELODY Primary Cohort were published in NEJM in March 2022.3

Results from the Phase IIb trial (Trial 03)
The primary endpoint of the Phase IIb study was met, reducing the incidence of medically attended LRTI caused by RSV by 70.1% (95% CI: 52.3, 81.2) compared to placebo. Observed events were 2.6% in treatment arm vs 9.5% in placebo arm. Between November 2016 and December 2017, 1,453 infants were randomised (Beyfortus, n=969; placebo, n=484) at the RSV season start. Research was conducted by AstraZeneca in both hemispheres, at 164 sites in 23 countries. Data were published in NEJM in July 2020.4

In a prespecified secondary endpoint, Beyfortus reduced medically attended RSV LRTI with hospitalisation by 78.4% (95% CI 51.9, 90.3) versus placebo. Observed events were 0.8% in treatment arm vs 4.1% in placebo arm. A post-hoc analysis of the Phase IIb study that applied the recommended 50mg dose in a subgroup of infants weighing less than 5kg showed the efficacy of Beyfortus against medically attended RSV LRTI and medically attended RSV LRTI with hospitalisation was 86.2% (95% CI 68.0, 94.0) and 86.5% (95% CI 53.5, 96.1) respectively.4

Beyfortus (nirsevimab) is a single dose long-acting antibody, developed and commercialised in partnership by AstraZeneca and Sanofi using AstraZeneca’s YTE technology. It is designed to protect infants born during or entering their first RSV season and for children up to 24 months of age who remain vulnerable to severe RSV disease through their second RSV season. Beyfortus, provided directly to newborns and infants as a single dose, offers rapid protection via an antibody to help prevent LRTD caused by RSV, without requiring activation of the immune system.

Beyfortus administration can be timed to the start of the RSV season.10

Beyfortus has been granted regulatory designations to facilitate expedited development by several major regulatory agencies around the world. These include Breakthrough Therapy Designation and Priority Review Designation by the China Center for Drug Evaluation under the National Medical Products Administration; Breakthrough Therapy Designation from the US Food and Drug Administration; access granted to the European Medicines Agency (EMA PRIority MEdicines (PRIME)) scheme; and 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 (AMED).

Sanofi Alliance
In March 2017, AstraZeneca and Sanofi announced an agreement to develop and commercialise nirsevimab. Under the terms of the agreement, AstraZeneca leads development and manufacturing activities, and Sanofi leads commercialisation activities and records revenue. The two companies share costs and profits in all territories except the US. AstraZeneca’s revenue from the agreement is reported as Alliance Revenue and Collaboration Revenue in the Company’s financial statements.

Following a revision to the profit-sharing arrangement relating to the development and commercialisation of nirsevimab in the US between AstraZeneca, Sanofi and Sobi, Sobi has entered into a direct relationship with Sanofi, replacing the previous participation agreement with AstraZeneca entered into in November 2018

AstraZeneca (LSE/STO/Nasdaq: AZN) is a global, science-led biopharmaceutical company that focuses on the discovery, development, and commercialisation of prescription medicines in Oncology, Rare Diseases, and BioPharmaceuticals, including Cardiovascular, Renal & Metabolism, and Respiratory & Immunology. Based in Cambridge, UK, AstraZeneca operates in over 100 countries and its innovative medicines are used by millions of patients worldwide. Please visit and follow the Company on social media @AstraZeneca.

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