The World Health Organization will work with travel and tourism industry representatives on Wednesday to draw up further recommendations to protect their crews so they can resume flights to China, a senior WHO official said.
Sylvie Briand, WHO director of global infectious hazard preparedness, said people infected with the coronavirus should wear masks, but that for other people without signs of the disease, "the masks will not necessarily protect them 100%".
Frequent hand-washing and other hygiene measures were needed, as the virus is spread by close contact and can also remain on surfaces, she said.
She dismissed earlier medical studies of some people having transmitted the disease without showing signs, saying they actually had "minor symptoms" that went undetected.