What’s the Deal With Covid-19 Nasal Sprays?

Multiple teams are pursuing a promising pathway for treatment

Credit: Evgenyi_Eg / Getty Images


On November 5, scientists at Columbia University in New York published a preprint showing that their nasal spray, squirted into the noses of ferrets, prevented Covid-19 infection. The study was small — only six ferrets got the spray — and it has not yet been peer-reviewed, but the findings are promising. When the treated ferrets were put into a cage with another ferret with Covid-19 for 24 hours, they did not get infected.


Scientists at Stanford University have a different idea for a molecule to spritz up the nose: antibodies from chickens. Much like humans, chickens produce antibodies as part of the immune response to a pathogen. As Science reported on November 10, the researchers injected the SARS-CoV-2 spike protein into the chests of chickens, waited for them to lay eggs, harvested antibodies from the yolks, then turned the antibodies into a nasal spray. The idea is that these antibodies can neutralize any virus particles that enter the nose. A Phase 1 trial in Australia to test the safety and longevity of the antibodies is currently underway. How long the antibodies will last in the nose remains an open question, though. While the nose is a major entryway for the virus, it also regularly sweeps its passages of foreign material, washing it down into the gut with mucus.


Yet another team, associated with a Seattle-based biotech company called Neoleukin Therapeutics, is developing a nasal spray containing a decoy molecule also meant to block ACE2. In a paper published in Science on November 5, they described their method of developing over 35,000 potential decoy molecules and whittling down the list to the best one. The decoy bears a close resemblance to the SARS-CoV-2 spike protein, which normally latches onto the ACE2 enzyme when trying to get into a cell.


A few teams are taking a different approach by attempting to administer a vaccine, rather than an antiviral treatment, through the nose (quick refresher: a vaccine is meant to elicit a natural immune response from the body to attack the virus, not block the virus directly).

Editor, Medium Coronavirus Blog. Senior editor at Future Human by OneZero. Previously: science at Inverse, genetics at NYU.