Wu Dong, deputy chief physician at Peking Union Medical College Hospital, said he has been treating critical patients in ICU since arriving in the city and the best advice he could give is that health workers must protect themselves both against the virus and the mental stress.

"In the last few days, we know that our European colleagues are also contracting the disease during their daily practice, and the proportion is similar to that during the early days of Wuhan," he said. "So we must protect our medical staffs."

Moreover, Wu said working in the ICU is a stressful job and the mortality rate of patients is relatively high. "Physicians may lose some of their patients no matter how hard they try to save their lives; this can easily damage morale," he said.

It is imperative that doctors are not overworked and try to rest and relax and recover from the exhaustion, he said. "Doctors should take very good care of themselves."