Major UK Trial Finds Surfactant Therapy Offers No Benefit for Severe Bronchiolitis

A UK-led clinical trial has determined that surfactant therapy, commonly used for premature babies with breathing difficulties, offers no benefit for infants receiving mechanical ventilation due to severe bronchiolitis. The Bronchiolitis Endotracheal Surfactant Study (BESS), the largest randomized trial of its kind, involved 232 critically ill babies across 15 hospitals in England, Scotland, and Northern Ireland. Researchers reported that the treatment did not reduce the duration of mechanical ventilation for these patients, despite being confirmed safe.

"Surfactant therapy did not provide significant advantages in improving outcomes for infants with severe bronchiolitis requiring mechanical ventilation."

The BESS Trial: Key Findings

The BESS trial, published on March 21, 2026, in The Lancet Respiratory Medicine, concluded that surfactant therapy did not provide significant advantages in improving outcomes for infants with severe bronchiolitis requiring mechanical ventilation. Professor Calum Semple, the study's lead, affirmed the treatment's safety but noted its lack of impact on the time babies needed mechanical ventilation.

The study was funded by the UKRI Medical Research Council (MRC), the National Institute for Health and Care Research (NIHR), and Chiesi Farmaceutici SpA, Italy.

Understanding Bronchiolitis

Bronchiolitis is a common seasonal viral illness, frequently caused by respiratory syncytial virus (RSV), and is a leading cause of infant hospital admissions in the UK during winter. It primarily affects babies under one year old, particularly those born prematurely.

While many infants recover with supportive care like oxygen and fluids, approximately 1,000 critically ill infants annually require intensive care and ventilation. Infants with bronchiolitis often exhibit reduced lung surfactant levels, a characteristic similar to premature babies with underdeveloped lungs.

Currently, specific treatments for bronchiolitis are unavailable, although an RSV vaccine is now offered to pregnant individuals.

Surfactant Therapy: An Established Treatment

Surfactant therapy is an established treatment in neonatal care, used to assist premature newborns with breathing by replenishing deficient lung surfactant. Researchers involved in the BESS trial maintain that surfactant therapy remains essential for premature newborns.

Future Outlook and Recommendations

The findings from the BESS trial are expected to inform future treatment approaches for severe bronchiolitis cases requiring intensive care. Researchers advocate for further studies to identify targeted treatments specifically for bronchiolitis.

Professor Semple has encouraged pregnant individuals to accept the RSV vaccine as a protective measure for their newborns.