In an update on the virus, which has so far killed a Saudi man and made a patient from Qatar critically ill, the United Nations health agency said it was working with international partners to understand the public health risk better.
"From the information available thus far, it appears that the novel coronavirus cannot be easily transmitted from person to person," it said in a statement.
The WHO put out a global alert on Sunday saying a new virus had infected a 49-year-old Qatari who had recently travelled to Saudi Arabia, where another man with the same virus had died.
The Qatari was described as critically ill on Tuesday and is being treated in a London hospital. No new confirmed cases of infection with the virus have since been reported, the WHO said.
The new virus shares some of the symptoms of SARS, or Severe Acute Respiratory Syndrome, another coronavirus, which emerged in China in 2002 and killed around a tenth of the 8,000 people it infected worldwide.
Both patients who have so far been confirmed with the new virus suffered kidney failure.