ENA Respiratory Begins Dosing in Phase 2 Community Study of INNA-051 Nasal Spray
ENA Respiratory has started dosing participants in a phase 2 community study of INNA-051, a dry-powder nasal spray being developed to strengthen the body’s natural antiviral defences and reduce the impact of symptomatic viral respiratory infections.
The company confirmed that the first participants have now received the investigational treatment, marking what it described as a key next step in building out the clinical evidence behind the once-weekly therapy.
INNA-051 is positioned as a virus-agnostic approach, intended to prime immune responses directly in the nose – often the first point of entry for respiratory viruses such as the common cold, influenza, RSV and coronaviruses.
By boosting these early “front-line” defences, the therapy aims to help the body respond faster after exposure, lowering the chances of infection becoming prolonged or complicated, particularly in people more vulnerable to severe illness.
The phase 2 trial – known as the POSITS study – will evaluate the safety, tolerability and efficacy of up to three months of treatment with INNA-051. It will also assess the spray’s effect on the incidence, duration and severity of symptomatic infections caused by common respiratory viruses in young adults considered at higher risk of exposure because they live or work in crowded environments.
In total, up to 1,100 generally healthy male and female participants are expected to be enrolled.
The study is structured in two stages. A 200-participant safety Phase A is underway during the current North American respiratory virus season, with weekly dosing for four weeks. A larger 900-participant Phase B is planned to follow next season, extending dosing over a three-month period to generate a broader picture of how the approach performs over longer community exposure windows.
Recruitment is focused on people living or working in high-exposure settings, including crowded households, university accommodation, military barracks and childcare centres – environments where respiratory viruses can circulate quickly and repeatedly.
Initial dosing took place at the Center for Vaccine Development and Global Health at the University of Maryland, Baltimore, with further recruitment taking place at the Naval Medical Research Command Clinical Trials Center in Bethesda, Maryland.
Commenting on the milestone, the company’s CEO said the start of the POSITS study represents an important step forward not only for the organisation, but for the broader development pathway of INNA-051.
They pointed to earlier pre-clinical and clinical work suggesting the spray has the potential to shorten the duration of symptomatic infections, help prevent progression into the lungs, and reduce complications – an ambition that, if borne out at scale, could be meaningful for populations facing repeated exposure.
The CEO also highlighted the continuing burden of respiratory viral illness, citing that there were more than one million hospitalisations and up to 200,000 deaths in the United States in 2025 from respiratory-related viral infections in such patients.
Framed in that context, ENA Respiratory believes that targeting the body’s natural host defence pathways through a simple, once-weekly nasal approach could offer a new option for millions of vulnerable patients worldwide.
Conclusion
With first dosing now underway, the POSITS phase 2 programme puts INNA-051 into a real-world community setting designed to test both safety and practical impact – measuring not just whether people tolerate the spray, but whether it can reduce how often symptomatic infections occur, how long they last, and how severe they become in high-exposure environments.
If the staged trial delivers supportive results across its current season safety phase and the larger follow-on cohort next season, ENA Respiratory will have taken a significant step toward validating a potentially scalable, virus-agnostic tool aimed at strengthening early nasal immunity and reducing the wider burden of respiratory viral disease.
News Credits: ENA Respiratory begins dosing in phase 2 study of INNA‑051 nasal spray
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