Bronchiolitis: Surfactant Treatment Shows No Benefit for Infants on Life Support – UK Trial

A major UK-led clinical trial has found that surfactant therapy, commonly used to aid premature babies’ breathing, offers no benefit to infants on life support with severe bronchiolitis. The findings, published today, March 21, 2026, in The Lancet Respiratory Medicine, represent the largest-ever randomized study of surfactant treatment for this common, and often serious, viral illness affecting babies.

Bronchiolitis, most frequently caused by respiratory syncytial virus (RSV), leads to the hospitalization of thousands of infants each winter in the UK. While most cases are mild, requiring only oxygen and fluids, around 1,000 of the most severely affected babies each year need intensive care and mechanical ventilation to support their breathing. The study, known as the Bronchiolitis Endotracheal Surfactant Study (BESS), investigated whether administering surfactant directly into the lungs of these critically ill infants could reduce the time they needed to remain on a ventilator.

What is Surfactant and Why Was It Studied?

Surfactant is a substance naturally produced in the lungs that helps maintain the tiny air sacs open, making breathing easier. Babies born prematurely often lack sufficient surfactant, which is why it’s routinely given to them to prevent respiratory distress. Since babies with bronchiolitis likewise exhibit reduced levels of surfactant, researchers hypothesized that supplementing it might improve their condition. The BESS trial, funded by the UKRI Medical Research Council (MRC), the National Institute for Health and Care Research (NIHR), and Chiesi Farmaceutici SpA, Italy, aimed to test this theory.

The trial involved 232 critically ill babies across 15 children’s hospitals in England, Scotland, and Northern Ireland. Despite the promising rationale, the study found that surfactant did not significantly reduce the duration of ventilation needed by these infants. Professor Calum Semple OBE, lead researcher from the University of Liverpool and Alder Hey Children’s NHS Foundation Trust, explained, “The treatment was safe, but it didn’t make any difference to how long babies stayed on ventilators. We had hoped that surfactant might speed up recovery for these very sick babies, but the evidence doesn’t support this.”

Study Design and Limitations

The BESS trial was a randomized, blinded, sham-controlled phase 2 trial. This means that babies were randomly assigned to receive either surfactant or a placebo (sham procedure), and neither the clinicians administering the treatment nor the researchers assessing the outcomes knew which babies received which treatment. The study ran over six winter seasons, from 2019 to 2024, to capture a broad range of bronchiolitis cases.

It’s important to note that this was a phase 2 trial, designed primarily to assess safety and explore potential efficacy. While the results are conclusive in showing no benefit in reducing ventilation time, further research may be warranted to investigate whether surfactant could have a role in specific subgroups of infants with bronchiolitis or when administered in combination with other therapies. The study’s findings do not negate the continued importance of surfactant therapy for premature infants, who have a different underlying lung physiology.

The Role of RSV and Current Prevention Strategies

RSV is the most common viral cause of bronchiolitis, particularly in infants under one year old. While most children experience RSV infection with mild, cold-like symptoms, it can be severe, especially in premature babies and those with underlying health conditions. Currently, there is no specific antiviral treatment for RSV infection. Management focuses on supportive care, such as oxygen therapy, hydration, and, in severe cases, mechanical ventilation.

However, a significant development in preventing severe RSV illness is the recent introduction of an RSV vaccine for pregnant women. As Professor Semple notes, “While we continue to research better ways to care for these sick babies, I urge Mums-to-be to accept the offer of the RSV vaccine during pregnancy, which will protect their newborn babies from severe bronchiolitis.” The vaccine works by stimulating the mother’s immune system to produce antibodies that are passed on to the baby, providing protection during the first few months of life. More information on the RSV vaccine can be found on the NHS website.

Implications for Clinical Practice and Future Research

The BESS trial provides clear evidence that routine surfactant administration does not improve outcomes for infants with severe bronchiolitis requiring life support. This finding is likely to influence clinical practice, preventing the use of a treatment that has been shown to be ineffective in this context.

Researchers emphasize that the need for improved treatments for bronchiolitis remains urgent. Future studies should focus on identifying targeted therapies that address the specific mechanisms underlying severe bronchiolitis, potentially exploring different surfactant formulations or combinations with other antiviral or anti-inflammatory agents. Further investigation into the role of the immune response in bronchiolitis could also lead to the development of novel therapeutic strategies. The study authors also suggest that continued surveillance of bronchiolitis cases and the effectiveness of preventative measures, such as the RSV vaccine, is crucial. You can find more details about the study on ScienceDirect.

What’s Next for Bronchiolitis Research?

The research team plans to continue analyzing the data collected during the BESS trial to explore potential biomarkers that could identify infants who might benefit from alternative therapies. They also intend to collaborate with other researchers to investigate the long-term effects of bronchiolitis and to develop more effective strategies for preventing and managing this common childhood illness. The findings also underscore the importance of ongoing investment in respiratory research to improve the health of infants and children. Additional information about the study can be found on Alder Hey Children’s NHS Foundation Trust’s website and EurekAlert!.