Contagion tells the story of the sudden appearance of a hyper-virulent strain of virus known as MEV-1.
MEV-1 is an airborne virus. If a person passes close enough to someone carrying the virus, and they breathe, they could contract the virus. It can also be contracted through tactile transmission. If a healthy person touches something a carrier touched, they could contract the virus. Between these two methods of transmission, and the fact that ground zero was the highly populated city of Hong Kong and patient zero was an international traveler, you have the recipe for disaster on a global scale.
And “Contagion” serves it all up for us in a stylistic, engrossing, high calibre movie experience.