Their guidance does not seem to suggest that people should not wear masks in public, nor does it comment on the effectiveness of doing so. From their site:

Their guidance does not seem to suggest that people should not wear masks in public, nor does it comment on the effectiveness of doing so. From their site: If you are healthy, you only need to wear a mask if you are taking care of a person with suspected 2019-nCoV infection. Wear a mask if you are coughing or sneezing. Masks are effective only when used in combination with frequent hand-cleaning with alcohol-based hand rub or soap and water. If you wear a mask, then you must know how to use it and dispose of it properly. https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public/when-and-how-to-use-masks https://www.who.int/emergencies/diseases/novel-coronavirus-2...