A nasal spray given once or twice a week could offer protection against coronavirus, according to new research.

Human trials could start within four months after studies on ferrets, led by an expert from Public Health England (PHE), found the spray could reduce infection and prevent transmission.

The therapy, developed by Australian biotech company Ena Respiratory, was originally developed to boost the natural immune system to fight colds and flu.

But trials showed that INNA-051 could reduce Covid-19 replication by up to 96% after it managed to boost the immune response prior to infection.

The new research, which has yet to be peer-reviewed, is published on the research site, medRxiv.

Ena Respiratory managing director, Dr Christophe Demaison, said: “We’ve been amazed with just how effective our treatment has been.

“By boosting the natural immune response of the ferrets with our treatment, we’ve seen a rapid eradication of the virus.

This is a significant development as the world races to find a solution to halt Covid-19 transmission and infection of at risk-populations

“If humans respond in a similar way, the benefits of treatment are two-fold.

“Individuals exposed to the virus would most likely rapidly eliminate it, with the treatment ensuring that the disease does not progress beyond mild symptoms.

“This is particularly relevant to vulnerable members of the community.

“In addition, the rapidity of this response means that the infected individuals are unlikely to pass it on, meaning a swift halt to community transmission.”

The firm said if human trials prove successful and funding is secured, the therapy could be rapidly manufactured at scale.

Professor Roberto Solari a respiratory specialist advisor to Ena Respiratory and visiting professor at Imperial College London, said: “This is a significant development as the world races to find a solution to halt Covid-19 transmission and infection of at-risk populations.

“Most exciting is the ability of INNA-051 to significantly reduce virus levels in the nose and throat, giving hope that this therapy could reduce Covid-19 transmission by infected people, especially those who may be pre-symptomatic or asymptomatic and thus unaware they are infectious.”