@kr61
When I travel by airline or I am in big crowds, I spray my nose first with a 1% Betadine and saline solution and gargle with Scope to prevent getting respiratory pathogens from replicating in my nose and throat. This seems to work for me. I don't get sick, or if I start getting early symptoms of a cold, I start doing this treatment three times a day and the symptoms disappear quickly.

Check with your pulmonologist to see if this may help you in your travels. Viruses go right through masks and masks restrict the flow of oxygen. I don't wear a mask when traveling.