UK researchers develop nasal spray that protects against Covid

A nasal spray that prevents infection from coronavirus as well as stopping people from infecting others has been developed by British researchers.

The University of Birmingham has developed a formula that catches the virus in the nose and then encapsulates it in a viscous coating from which it cannot escape to cause infection. It means the virus would be harmless if it entered the respiratory tract and safe for a person to breathe out because it would already be inactive even if inhaled by another person.

Cell-culture laboratory experiments showed that the spray prevented infection for up to 48 hours, and the team believes it could be useful in areas in which crowding is unavoidable, such as aeroplanes and classrooms.

Researchers deliberately chose ingredients that are already approved for medical use, meaning the spray is safe to be used by humans. They now want to find a distribution partner and plan more trials to check that it has the same protective effect in humans as seen in the lab.

"With the right partners, we could start mass production within weeks," said Dr Richard Moakes, of Birmingham University. "We engineered the product using materials which we knew were both food and pharma approved. This means that we know that large amounts of the polymers can be ingested without toxic effects. 

"We have tried to formulate the material so that it will cling to the inside of the nasal cavity for as long as possible.  Current nasal sprays are typically reapplied four times per day, and we would expect similar for this product.

"The data that we have collected shows that the active component is potent at very low concentrations, so the retention of even a thin layer would likely have a positive effect."

Researchers believe using the spray four times a day would be enough for general protection, although it is safe enough to be applied every 20 minutes if in a high-risk environment.

The spray is a combination of an antiviral agent called carrageenan, commonly used in foods as a thickening agent, and a solution called gellan –  a gelling agent  selected for its ability to stick to cells inside the nose.

Gellan is an important component because it has the ability to be sprayed into fine droplets inside the nasal cavity, where it can cover the surface evenly and stay at the delivery site rather than sliding downwards and out of the nose.

Professor Liam Grover, the study’s co-author, said: "Although our noses filter thousands of litres of air each day, there is not much protection from infection and most airborne viruses are transmitted via the nasal passage. The spray we have formulated delivers that protection but can also prevent the virus being passed from person to person."

However, the researchers stressed that hand-washing remained important because Covid could still be picked up through touch. 

"Products like these don’t replace existing measures such as mask-wearing and hand-washing, which will continue to be vital to preventing the spread of the virus," added Dr Moakes. "What this spray will do, however, is add a second layer of protection to prevent and slow virus transmission."

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