A nasal spray that can provide effective protection against the coronavirus that causes COVID-19 has been developed by British researchers, using materials already cleared for use in humans.

A team at the University of Birmingham formulated the spray using compounds already widely approved by regulatory bodies in the United Kingdom, Europe and the United States, and widely used in medical devices, medicines and even food products.

This means that the normal complex procedures to take a new product to market are greatly simplified, so the spray could be commercially available very quickly.

A pre-print study describes cell culture experiments designed to test the ability of the solution to inhibit COVID-19 infection. The research showed that cell-virus cultures inhibited the infection up to 48 hours after being treated with the solution and when diluted many times.

The team believes the spray could be particularly useful in areas where crowding is less avoidable, such as in airplanes or classrooms, and regular application of the spray could significantly reduce disease transmission.

Richard Moakes, lead author of the study, said: "This spray is made from readily available products that are already being used in food products and medicines and we purposely built these conditions into our design process. It means that, with the right partners, we could start mass production within weeks."

The spray is composed of an antiviral agent called carrageenan, commonly used in foods as a thickening agent, and a solution called gellan, which was 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 downward and out of the nose.

Airborne pathogens pose high risks in terms of both contraction and transmission within the respiratory pathways, in particular the nasal region. Although airborne transmission has been known about for some time, there is little in the way of adequate intervention that can protect the individual, or even prevent further spread.

The spray developed by Birmingham University catches and coats the virus inside the nose, from where it can be eliminated either by noseblowing or swallowing.

And because the virus is encapsulated in the spray's viscous coating, it is prevented from being up - taken by the body. That means it will reduce the viral load in the body, but also even if virus particles are passed on to another person via a sneeze or cough, that person is less likely to be infected by active virus particles.

Co-author Liam Grover said: "Although our noses filter thousands of liters 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 the existing preventative measures still remain important.

"Products like these don't replace existing measures such as mask wearing and handwashing, which will continue to be vital to preventing the spread of the virus," Moakes said.