A few years ago, one of my sisters talked to a stewardess about viruses on planes.
The stewardess said she and her colleagues fended off viral infections by using a
cue tip Q-TIP (thank you, gasstationwithoutpumps!) to apply Ayr Saline Nasal Gel with Soothing Aloe to their nasal passages. My sister has been using that advice for flights ever since.
Our urgent care center told Ed that saline gels help prevent nose bleeds. I have no idea whether it also creates a barrier to viruses–or, if it does, whether it does so for COVID 19 specifically.
But I’m passing it along.