Evidence is mounting that camels play a key role in spreading Middle East respiratory syndrome (MERS) virus, and the camel-borne threat may extend far beyond the Middle East. As a result, scientists are shifting their focus from human cases to camels. One idea gaining traction is to vaccinate camels. But vaccines against coronaviruses, the group to which MERS belongs, are difficult to make, and researchers face multiple hurdles. To make matters worse, there are very few labs capable of safely studying deadly viruses in animals as big and unruly as camels.