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# Draft Guide on Developing RSV Drugs
- URL: https://www.fdaweb.com/draft-guide-on-developing-rsv-drugs/
- Published: 2017-10-11T12:00:00.000Z
- Updated: 2026-09-14T22:55:20.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5139845

FDA has published a [draft guidance ](https://www.fda.gov/downloads/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/UCM579756.pdf?ref=fdaweb.com)on “Respiratory Syncytial Virus (RSV) Infection: Developing Antiviral Drugs for Prophylaxis and Treatment” that addresses the agency’s current thinking about the overall development program and clinical trial designs for such products. It focuses primarily on the development of drugs with antiviral mechanism for RSV-related illness in infants and young children (e.g., bronchiolitis), but it also briefly touches on other populations.

The guidance says that in the absence of a generally accepted standard-of-care antiviral treatment for acute bronchiolitis in infants and children, a randomized, double-blind, placebo-controlled trial in infants may be appropriate to demonstrate the drug’s efficacy. “In this case,” it says, “the investigational drug could be added to the current standard-of-care treatment (currently supportive care) compared to standard-of-care therapy plus placebo. In circumstances where aerosolized ribavirin is considered the standard of care for RSV bronchiolitis, the investigational drug can be evaluated as an add-on therapy to aerosolized ribavirin and compared to aerosolized ribavirin and placebo in a superiority trial. Noninferiority trials comparing the investigational drug to ribavirin are not feasible because the registrational ribavirin trials used endpoints that are no longer clinically relevant and do not allow for calculation of a noninferiority margin.”

The document notes that after anti-RSV drugs become available for treatment, placebo-controlled trials may no longer be appropriate (e.g., trials evaluating serious or life-threatening infection), and trials should include an active control arm using a superiority or noninferiority design. “If a noninferiority design is proposed, justification for the noninferiority margin should be submitted to the \[drug review division\] for review and concurrence.”