San Francisco had the 1918 flu under control. And then it lifted the restrictions.

When the clock struck noon, the masks came off.
It was Nov. 21, 1918, and San Francisco residents gathered in the streets to celebrate not only the recent end of World War I and the Allies’ victory, but also the end of an onerous ordinance that shut down the city and required all residents and visitors to wear face coverings in public to stop the spread of the so-called Spanish flu.