Intranasal Spray to Prevent Illnesses from Respiratory Viruses

Respiratory viruses such as influenza and COVID-19 hospitalize more than one million people in the U.S. each year, with many infections spreading through close contact in households, schools, and workplaces. People regularly exposed to young children or crowded environments face an especially high risk. Current preventive strategies largely focus on virus-specific vaccines, leaving gaps when multiple pathogens circulate. A new clinical trial is now testing a preventive nasal therapy designed to strengthen the body’s frontline immune defenses before infection takes hold.

Led by the University of Maryland School of Medicine (Baltimore, MD, USA), in collaboration with industry partner ENA Respiratory (Melbourne, VC, Australia), the randomized double-blind Phase 2 trial will enroll 1,100 healthy adults aged 18 to 45 who are at increased risk of respiratory infections. Participants will receive either the experimental intranasal spray or a placebo to evaluate safety, immune activation, and illness prevention.

The investigational therapy is a non-vaccine, virus-agnostic intranasal spray designed for weekly use during cold and flu season. It works as a TLR2/6 agonist, priming the immune system’s first line of defense at the nasal mucosa. By acting at the initial site of viral entry and replication, the spray aims to accelerate pathogen clearance before infection can become established.

This Phase 2 trial will assess whether the therapy reduces the likelihood or severity of respiratory illness compared with placebo. Researchers will monitor immune responses and clinical outcomes throughout the respiratory virus season. While results are pending, the study builds on earlier evidence suggesting that strengthening mucosal immunity could protect against multiple respiratory pathogens. The trial is designed to provide clear safety and efficacy data in a real-world exposure setting.

If successful, the approach could complement existing vaccines by offering broad, early protection against diverse respiratory viruses. Such a strategy may be especially valuable for people with frequent exposure risks or underlying conditions that increase complication rates. Researchers also see potential for this immune-priming approach to improve preparedness for future respiratory outbreaks. Further trials could expand testing to older adults and higher-risk populations.

“This study represents a new approach to reducing illness from respiratory infections,” said Professor Justin Ortiz, MD, principal investigator of the trial. “Instead of targeting a single virus, this strategy strengthens the body’s early immune defenses, which may help mitigate disease caused by multiple respiratory pathogens.”

Related Links:
University of Maryland School of Medicine
ENA Respiratory