Since December, health authorities in China have been grappling with an outbreak of viral pneumonia that has sickened hundreds of people and killed 26 as of Thursday.
The disease is thought to be caused by a previously unknown type of coronavirus that may have first spread to humans from animals at a now-shuttered seafood market in the central Chinese city of Wuhan, where most of the cases have been diagnosed. Further cases have been confirmed in Thailand, Vietnam, Japan, South Korea, Singapore and the U.S. while suspected cases have also occurred in a number of other countries and territories.
Coronaviruses are a family of viruses that can cause a variety of ailments, among them the deadly severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). Most known coronaviruses cause relatively mild cold-like symptoms, but their ability to jump between humans and animals makes them hard to contain. Chinese health officials have confirmed that the new virus can spread between people, but do not believe it to be as serious as SARS or MERS.