BANGKOK: As fears of a deadly virus sweep the globe, panicked members of the public are depending on a flimsy first line of defense — surgical masks that are coveted but in short supply and of limited use.

While Asian commuters cover their noses and mouths with the blue-green paper-thin covers — and social media buzzes with mask emojis, rumors of stockpiles and shortages — the humble medical mask has become an essential weapon in the battle against an invisible enemy.