
On July 17, 2023, the U.S. Food and Drug Administration (FDA) approved nirsevimab (brand name: Beyfortus) for the use of preventing respiratory syncytial virus (RSV) in newborns and infants. Each year in the United States, RSV is the leading cause of hospitalization in babies under a year old.
Beyfortus can be administered at birth to infants who are born during RSV season or given later to infants who need protection leading up to RSV season. The FDA also approved a second injection for children up to 2 years old, who are especially vulnerable to RSV.
Approximately 58,000–80,000 children younger than 5 years old are hospitalized each year due to RSV infections, according to the Centers for Disease Control and Prevention (CDC). An additional 2 million outpatient (non-hospitalization) visits occur in children younger than 5 years old.
“RSV can cause serious disease in infants and some children and results in a large number of emergency department and physician office visits each year,” said John Farley, MD, MPH, director of the Office of Infectious Diseases in the FDA’s Center for Drug Evaluation and Research. “Today’s approval addresses the great need for products to help reduce the impact of RSV disease on children, families and the health care system,” Farley said.
Developed by AstraZeneca and Sanofi, Beyfortus is not a vaccine, but rather a single-injection ready-made antibody that will keep RSV from multiplying or attacking healthy cells. Whereas vaccines prompt people’s immune systems to create protective antibodies, Beyfortus will be immediately effective without requiring a baby’s immune system, which is naturally weaker, to do additional work.
Prior to Beyfortus, palivizumab (brand name: Synagis) was the only antibody injection, but it was only available for premature babies 6 months or younger. In addition to its limited access, Synagis’ efficacy was short-term, wearing off after about a month. Beyfortus is a stabilized antibody, so it can last up to 6 months (the average length of an RSV season), and it will be broadly available to all newborns and infants.
The FDA’s approval of Beyfortus was based on an in-depth clinical development program and an extensive study that included three late-stage trials. The pivotal results proved the drug’s efficacy and safety. The most common side effects were injection site reactions, such as rash.
Next up, the Advisory Committee on Immunization Practices (ACIP) has put forth recommendations to the CDC, which is expected to sign off on the drug. AstraZeneca and Sanofi expect Beyfortus to be available in the fall, in advance of this year’s RSV season. Beyfortus received approval in the European Union in fall of 2022. It is currently under review in China, Japan and several other countries.
Beyfortus’s approval is yet another sign of the FDA’s recent efforts in protecting the population against RSV and helping to lessen the burden of health care providers and systems. On May 31, 2023, it approved ABRYSVO, a vaccine that protects adults 60 years of age and older against RSV. The FDA is also reviewing an RSV vaccine for pregnant people. It would be administered in the third trimester, so its antibodies could travel through the placenta to provide even earlier protection to the baby.