sciinfo

"The Metropole Hotel hastened the international spread of the 2003 SARS outbreak by the index case infecting visitors from Singapore, Vietnam, Canada as well as local people via close contact with the index case and the environmental contamination. The one-week quarantine of more than 300 guests and staff at the Metropark Hotel during the 2009 H1N1 swine flu exposed gaps in the partnership with the hotel industry. The subsequent guidelines for the hotel industry from the Centre of Health Protection focused largely on the maintenance of hygiene within the hotel premises."

Since only around 20% of patients require hospitalization, we can estimate there are ~5 infected in her cohort. With doubling time outside China at 5-6 days, that means around 3 doublings: 2^3 * 5 = 40 infected today (Many of them will not show serious symptoms; some who will require admission have not progressed to that stage yet.) So far we have assumed that all hospitalized cases are detected, however.

Some who are hospitalized might still not be detected, since without a test or a CT scan, its symptoms are similar to other viral pneumonia. Let's say infected per detected is a factor of 1.5-4. Very rough estimates: ~60-160 infected in the Bay Area now.

The first hypothesis is likely based on the number of infections found in international travellers who went to Iran. We still cannot rule out the second hypothesis though.