Newly Approved Monoclonal Antibody Prevents RSV in Babies and Toddlers

On July 17, 2023, the FDA added to the arsenal of respiratory syncytial virus (RSV) prevention tools by approving Beyfortus, a monoclonal antibody for preventing the infection in children two years old or younger.  

According to the press release, one dose of the drug given via intramuscular injection before or during RSV season can protect against the virus.  

Three clinical trials supported the approval of this drug. Its efficacy was evaluated based on the number of medically attended RSV lower respiratory tract infections (MA RSV LRTI) within 150 days of drug administration. MA RSV LRTI included infections that required any provider visit. Other requirements included a severe lower respiratory tract disease and a positive RSV test.  

Two trials, Trial 03 and 04, were randomized, double-masked, placebo-controlled, multicenter clinical trials. In Trial 03, the researchers recruited over 1,400 preterm infants born during or just before the RSV season. Approximately 484 infants received a placebo, while 969 received a single injection of Beyfortus.  

Only 2.6% of infants receiving Beyfortus experienced MA RSV LRTI. Meanwhile, significantly more infants, 9.5%, receiving the placebo had MA RSV LRTI.  

Trial 04 focused on infants born at term or late preterm infants. The researchers gave 994 infants Beyfortous while 496 received a placebo. Patients receiving the placebo were significantly more likely to experience MA RSV LRTI, with a risk of 5.0% compared to 1.2%.  

The final trial was a randomized, double-blind, active (palivizumab)-controlled, multicenter trial that recruited 925 individuals under two years old at a high risk of RSV infection in their second season. Most participants included preterm infants, those with chronic lung disease of prematurity, or individuals with congenital heart disease. The drug’s efficacy and safety in this population supported its approval.  

Despite the benefits of the medication, there is a risk of injection site reactions and contraindications for children with a history of hypersensitivity reactions.  

“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, in the FDA press release. “Today’s approval addresses the great need for products to help reduce the impact of RSV disease on children, families, and the healthcare system.”