The mystery coronavirus can be transmitted between humans, China confirmed late on Monday night as the death toll from the mysterious virus rose to three, the total number of infected crossed the 225-mark and the outbreak spread across the country including to Beijing and Shanghai.

Chinese President Xi Jinping on Monday instructed state officials to prioritize “the safety and health of people” and ordered “resolute efforts” to stop the spread of the virus.

The virus causes pneumonia in those who contract it. Four deaths are reported so far in China, with more than 200 people infected to date, according to Chinese data. But symptoms appear less severe than those seen during the SARS outbreak nearly two decades ago.

As many as 14 medical workers were infected by the disease, health officials said, a sign that the disease is highly infectious.

Zhong Nanshan, director of the State Key Laboratory of Respiratory Disease said transmission between humans was behind at least one confirmed case in Wuhan and also infections in two families in south China’s Guangdong province.

Zhong added said 14 medical staff contracted the virus from one carrier without giving details.

Zhong added that at least 95 percent of the cases were connected to Wuhan, the capital of the central Chinese province of Hubei.

He said the occurrence of human-to-human and infection of the medical staff infection were “important signs” and the priority should be to prevent the spread of the disease.

A Chinese woman was hospitalised with the Coronavirus in South Korea’s Seoul on Monday after disembarking from a flight from the city of Wuhan in central China where the virus is said to have originated.

One person in Japan and two more in Thailand have also been diagnosed with the disease.