What does Taiwan say? We should follow leaders like Taiwan: they were at huge risk, yet economy is running and schools open, their VP is an epidemiologist and he was minister of health during their SARS outbreak. Taiwan’s CDC says: “Prevention is the same as for other respiratory infections including washing hands frequently, wearing masks and cleaning up secretion from the mouth and nose appropriately. Other measures include avoiding crowded places such as markets or local hospitals, avoiding contact with animals and dead animals and avoiding eating raw meat or eggs. Additionally, you should wear masks and attend medical attention immediately when flu-like symptoms occur (such as body temperature ≧38℃, and coughing, etc)” - https://www.cdc.gov.tw/En/Category/QAPage/LnqBFJsulw6fW3nswc... and “Our guidelines and policy for wearing masks have not changed, but people should consider wearing a mask in enclosed crowded spaces with poor air ventilation,” Minister of Health and Welfare Chen Shih-chung (陳時中), who heads the center, told a news conference in Taipei. People who must attend events in small crowded venues, where they would have frequent and close contact with other people, are advised to wear a mask, he said.”. Of course Taiwan also has many other layers of effective control against Covid: https://www.dw.com/en/taiwan-coronavirus/a-52724523 and a wired article too: https://www.wired.com/story/taiwan-is-beating-the-coronaviru...
Also i think it is significant that citizens commonly wear masks in the countries that are most successful at controlling the virus (and haven’t shut down their economies, Taiwan, Vietnam, SK, Singapore, Japan). It is a social stigma to not wear a mask in some places. However, although Japan looks like they have slowed the outbreak maybe they are just at the corner of the hockey stick. And in HK: “Dr. Pak-Leung Ho, head of Centre for infection at @hkumed ... highlighted universal mask-wearing as one of the reasons widespread outbreak didn't occur.” https://twitter.com/lwcalex/status/1235091542219448321
There is a huge back-pressure against wearing masks in western countries, which leads to an environment of glib advice against them. I know this isn’t a very scientific issue, but I think it matters. https://www.nytimes.com/2020/03/17/opinion/coronavirus-face-... and “Why some countries wear face masks and others don't” https://www.bbc.com/news/world-52015486
Finally, here is a sciency article “Would everyone wearing face masks help us slow the pandemic?”: https://www.sciencemag.org/news/2020/03/would-everyone-weari...