Why MERS virus is so scary

The head of the World Health Organization warned the world this week of a new virus, awkwardly dubbed MERS-CoV, found in Saudi Arabia.

"Looking at the overall global situation, my greatest concern right now is the novel coronavirus," Margaret Chan said, calling it "a threat to the entire world."

"We understand too little about this virus when viewed against the magnitude of its potential threat," the director general said in her closing speech to the 66th session of the World Health Assembly. "Any new disease that is emerging faster than our understanding is never under control.