I saw this article in the NY Times last November, which, though different, is also a fascinating common sense concept for a SARS-CoV2 blocking nasal spray. I'll paste the rather short article in this comment:
Nasal Spray Prevents Covid Infection in Ferrets, Study Finds
Scientists at Columbia University have developed a treatment that blocks the virus in the nose and lungs, is inexpensive and needs no refrigeration.
NYT Nov. 5, 2020
A nasal spray that blocks the absorption of the SARS-CoV-2 virus has completely protected ferrets it was tested on, according to a small study released on Thursday by an international team of scientists. The study, which was limited to animals and has not yet been peer-reviewed, was assessed by several health experts at the request of The New York Times.
If the spray, which the scientists described as nontoxic and stable, is proved to work in humans, it could provide a new way of fighting the pandemic. A daily spritz up the nose would act like a vaccine.
“Having something new that works against the coronavirus is exciting,” said Dr. Arturo Casadevall, the chairman of immunology at the Johns Hopkins Bloomberg School of Public Health, who was not involved in the study. “I could imagine this being part of the arsenal.”
The work has been underway for months by scientists from Columbia University Medical Center in New York, Erasmus Medical Center in the Netherlands and Cornell University in Ithaca, N.Y., The study was funded by the National Institutes of Health and the Columbia University Medical Center.
The team would require additional funding to pursue clinical trials in humans. Dr. Anne Moscona, a pediatrician and microbiologist at Columbia and co-author of the study, said they had applied for a patent on the product, and she hoped Columbia University would approach the federal government’s Operation Warp Speed or large pharmaceutical companies that are seeking new ways to combat the coronavirus.
The spray attacks the virus directly. It contains a lipopeptide, a cholesterol particle linked to a chain of amino acids, the building blocks of proteins. This particular lipopeptide exactly matches a stretch of amino acids in the spike protein of the virus, which the pathogen uses to attach to a human airway or lung cell.
If you're a molecular biologist, the simplicity, elegance, & OMG, what an obvious idea! should be immediately obvious. I don't know what part of the Spike they are matching & whether that is in an area under selective pressure. You should ask them!