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A hospital worker wearing a face shield and mask is seen at a COVID-19 assessment centre for staff at Lions Gate Hospital, in North Vancouver, on March 19, 2020.

DARRYL DYCK/The Canadian Press

In the race to find a treatment that works against COVID-19, scientists have been testing drugs that impede viruses in human cells as well as those that can calm the immune system so that the body’s response to infection is less severe.

Now, a Canadian company is trying a different strategy. Using a specially engineered nasal spray, it hopes to make subjects’ airways a hostile environment for the virus so that an infection can’t get started.

The company, SaNOtize Research and Development Corp. of Vancouver, announced on Wednesday that it has received approval from Health Canada to begin a clinical trial of its method, which hinges on the delivery of nitric oxide gas to the upper-respiratory tract.

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The chemical, which has antiviral properties, is released from a liquid solution developed by the company and which can be used in different ways, including as a nasal spray. Laboratory tests conducted last week at the Institute for Antiviral Research at Utah State University show the solution is effective against the virus that causes COVID-19.

If the same approach works in people, it opens the door to a preventative treatment for those who are at high risk of exposure to COVID-19, including front-line health care workers. More broadly, it could help protect anyone in a public setting once physical-distancing measures are lifted.

“We are trying to rapidly move this forward and provide a prevention that would help us resume social and economic activity while we wait for a vaccine to be developed,” said Chris Miller, the company’s chief science officer, who has been studying nitric oxide’s potential as an antimicrobial agent since the 1990s.

That hope is balanced by the reality that, so far, no drug has been shown to be safe and effective for treating COVID-19 according to treatment guidelines released on Tuesday by the U.S. National Institutes of Health.

Nitric oxide – not to be confused with nitrous oxide or laughing gas – is a simple molecule consisting of one nitrogen and one oxygen atom. Because of its small size and biochemical properties, it easily penetrates cells and plays multiple roles in the human body.

One of those roles is to serve as a short-range weapon against foreign invaders when it is produced by immune cells. Nitric oxide has also been shown to deter viruses, including influenza and, in one 2009 study, the SARS coronavirus.

Dr. Miller said that the tiny but reactive molecule is thought to alter the coronavirus’s protruding crown of proteins that it uses to latch onto cells. Inside cells, it can also interfere with the virus’s ability to replicate.

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In a hospital environment, the gas can be delivered safely to a patient’s respiratory tract from a pressured cylinder. This method is now being investigated at a number of sites as a potential treatment for those with COVID-19 infections. In one randomized trial, led by Massachusetts General Hospital in Boston, nitric oxide is also being administered to hospital workers for 15 minutes before and after their shifts to test whether it reduces their rate of infection.

“We’re hoping that will prevent caregivers from developing the disease,” Robert Kacmarek, the hospital’s director of respiratory care, said in an interview with Boston’s WBUR radio.

Where SaNOtize differs is in the use of a solution that releases nitric oxide at the required dose and at the point where it’s needed without hospital equipment or expert supervision.

Dr. Miller said the clinical trial, which could begin recruiting subjects as early as next week, would test a combined use of the solution through daily gargling, a thorough nasal rinse and repeated application as a nasal spray.

“It’s much like hand sanitizer for the nose,” he said.

The trial will determine if a group of subjects in a high infection-risk environment are less likely than a control group to develop symptoms of COVID-19. Those in the control group who become infected will then be offered the solution as a form of early treatment in a separate arm of the trial.

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Before the COVID-19 outbreak, Dr. Miller said he and his colleagues were testing the solution as a treatment for chronic sinusitis. This prior work allowed them to pivot quickly when the pandemic hit.

Outside of humans, the company has also been testing the solution for effectiveness at preventing shipping fever, a cattle ailment caused by a combination of bacterial and viral infections.

John Church, a researcher at Thompson Rivers University in Kamloops, B.C., who is collaborating on the cattle tests, said the solution performed as well as antibiotics at reducing infections.

“I was really quite surprised a how long lasting the effect was,” he said.

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