Offices are closing temporarily and companies are asking employees to work from home in an attempt to contain the disease.
The city's tech conferences are also being canceled.
Many of them were planned to take place at the city's Moscone Center, one of the city-owned facilities affected by the order banning large-scale events.
There are at least 554 confirmed cases in the US, with 21 reported deaths.
One of them was an elderly person in Sacramento, California. The person had just returned from a cruise aboard the Grand Princess cruise ship, where 21 passengers have since been tested for and confirmed to have been infected by the virus. The ship is set to dock in Oakland Monday.
The Grand Princess is not to be confused with the Diamond Princess, a cruise ship whose passengers were quarantined first onboard in Japan and then at the Travis Air Force Base in Fairfield on the outskirts of the Bay Area.
Source: Business Insider