This site claims that this action will help prevent you getting sick during air-travel:
try applying a small amount of Neosporin or petroleum jelly just inside the nostrils (use a Q-tip if your hands aren't freshly washed).Experts say the antibacterial action of Neosporin is unlikely to present much of a barrier when used in this way, but it never hurts to moisturize the inside of the nose
Is there any validity to this claim?
Related: Can triple antibiotic ointment in the nostrils prevent flu?