Once testing actually ramps up in the US... I'd expect similar cases to pop up all over the Bay Area. The Fairfield case was infectious starting weeks ago.

The CDC site shows only 8 more tests having happened in the last few days (aka: preposterously low!). We're really flying blind until we have more data and testing. When the history of this epidemic in the US is written, it will be noted that the entire month of February was wasted diagnostically and critical opportunities to still attempt containment lost.