The new virus, known as novel coronavirus, or nCoV, is from the same family of viruses as those that cause common colds and the one that caused the deadly outbreak of Severe Acute Respiratory Syndrome (SARS) that emerged in Asia in 2003.

“This is the first time health care workers have been diagnosed with (novel coronavirus) infection after exposure to patients,” the Geneva-based U.N. health agency said in a disease outbreak update late on Wednesday.

The health workers are a 45-year-old man, who became ill on May 2 and is currently in a critical condition, and a 43-year-old woman with a coexisting health condition, who fell ill on May 8 and is in a stable condition, the WHO said.