World Health Organization officials Monday said they still recommend people not wear face masks unless they are sick with Covid-19 or caring for someone who is sick.

"There is no specific evidence to suggest that the wearing of masks by the mass population has any potential benefit. In fact, there's some evidence to suggest the opposite in the misuse of wearing a mask properly or fitting it properly," Dr. Mike Ryan, executive director of the WHO health emergencies program, said at a media briefing in Geneva, Switzerland, on Monday.

"There also is the issue that we have a massive global shortage," Ryan said about masks and other medical supplies. "Right now the people most at risk from this virus are frontline health workers who are exposed to the virus every second of every day. The thought of them not having masks is horrific."

Dr. Maria Van Kerkhove, an infectious disease epidemiologist with the WHO, also said at Monday's briefing that it is important "we prioritize the use of masks for those who need it most," which would be frontline health care workers.

"In the community, we do not recommend the use of wearing masks unless you yourself are sick and as a measure to prevent onward spread from you if you are ill," Van Kerkhove said.

"The masks that we recommend are for people who are at home and who are sick and for those individuals who are caring for those people who are home that are sick," she said.

World Health Organization officials warned at a media briefing last week that globally there is a "significant shortage" of medical supplies, including personal protective gear or PPE, for doctors.

"We need to be clear," Van Kerkhove said last week. "The world is facing a significant shortage of PPE for our frontline workers -- including masks and gloves and gowns and face shields -- and protecting our health care workers must be the top priority for use of this PPE."