Published on: 2025-06-24 | Written by:
In a long-anticipated move, the U.S. Food and Drug Administration (FDA) has officially approved Clesrovimab (brand name: Enflonsia)—the first preventive monoclonal antibody designed to protect infants from Respiratory Syncytial Virus (RSV), a leading cause of lower respiratory tract infections in children under one year of age.
RSV (Respiratory Syncytial Virus) is a seasonal virus that infects the respiratory tract. It is the most common reason for infant hospitalizations, causing:
Bronchiolitis
Pneumonia
Severe shortness of breath
Recurrent respiratory distress
Most cases occur during the winter months, primarily affecting infants with immature immune systems, especially premature babies or those with chronic conditions.
Clesrovimab is a monoclonal antibody designed to be injected into infants to prevent RSV from binding to respiratory cells. Key features include:
A single dose given ahead of the RSV season
Protection that lasts for several months
Over 80% reduction in hospitalization and infection rates
The drug proved highly effective in clinical trials involving thousands of infants from diverse ethnic and health backgrounds.
Clesrovimab works by blocking the virus from entering human cells. It binds to a specific part of the RSV protein, preventing it from attaching to respiratory cells. As a result:
The virus cannot replicate
Symptoms are significantly reduced
The risk of severe complications is minimized
In a large-scale study involving over 3,000 infants:
RSV infection rates dropped by 83% compared to unprotected infants
No serious side effects were reported
The drug was especially effective in premature infants
RSV causes millions of infections and hundreds of thousands of hospitalizations in children each year.
Until now, no effective preventive treatment was available for infants.
The approval of Enflonsia marks a new era in early prevention of respiratory illnesses in children.
The FDA’s approval of Clesrovimab (Enflonsia) marks a major breakthrough in pediatric preventive care, offering vulnerable infants protection from the dangers of RSV. This innovation gives healthcare providers and parents a powerful new tool to safeguard infant health—and represents a major step forward in the quest for safer, healthier childhoods.