RSV Antibody Prevents Severe Infections: Microbial Minutes

Aug. 7, 2023

The U.S. Food and Drug Administration (FDA) approved a new monoclonal antibody that prevents severe respiratory syncytial virus (RSV) infections in infants. But how—and how well—does it work?

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Infections caused by respiratory syncytial virus (RSV) are the most common cause of lower respiratory tract infections (LRTI) in infants, leading to thousands of hospitalizations every year. The U.S. Food and Drug Administration (FDA) approved a new drug—a monocolonal antibody called nirsevimab—for preventing RSV LRTI in infants. But how effective is it? When will the drug become available for clinical use? What other tools are being developed to prevent severe infections as the next RSV season looms large? Key take-aways and resources used in this Microbial Minutes are listed below.

Key Take-Aways

  • The U.S. FDA approved a new monoclonal antibody—nirsevimab—for preventing RSV LRTI in infants.
  • While there is already an antibody (paliviziumab) used to protect high-risk infants from RSV LRTI, it prevents hospitalization ~50% of the time & must be administered monthly.
  • Nirsevimab is approved for use in a broader range of infants, lowers risk of RSV LRTI requiring medical attention by ~70% and provides protection throughout the RSV season. Only 1 injection is required.
  •  Additional preventive tools (e.g., maternal RSV vaccines) may also be available soon. 


  • Catan N. Pfizer’s RSV Vaccine for Pregnant Women Wins FDA Panel Support. Time. May 19, 2023.
  • Dhagat P. and Rohde R. Respiratory Syncytial Virus (RSV), Tis the Season. American Society for Microbiology. Dec. 6, 2022. 
  • Goodman B. FDA approves antibody to protect infants from RSV. CNN. July 17, 2023
  • Pfizer. U.S. FDA Approves ABRYSVO™, Pfizer’s Vaccine for the Prevention of Respiratory Syncytial Virus (RSV) in Older Adults. Pfizer. May 31, 2023.
  • Romo V. RSV is surging. Here's what to watch for and answers about treatment options. NPR. Nov. 2, 2022.
  • Satija B. and Mahobe R. EU regulator backs Pfizer's RSV vaccine for infants, older adults. Reuters. July 21, 2023.
  • U.S. Centers for Disease Control and Prevention. RSV in Infants and Young Children. CDC. June 5, 2024.
  • U.S. Food and Drug Administration. June 8, 2023 Meeting of the Antimicrobial Drugs Advisory Committee-FDA Briefing Document. FDA. June 8, 2023.
  • U.S. Food and Drug Administration. FDA Approves First Respiratory Syncytial Virus (RSV) Vaccine. FDA. May 03, 2023.
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Author: Madeline Barron, Ph.D.

Madeline Barron, Ph.D.
Madeline Barron, Ph.D. is the Science Communications Specialist at ASM. She obtained her Ph.D. from the University of Michigan in the Department of Microbiology and Immunology.