Stanford did a study looking for Coronavirus cases in Jan and Feb in the Bay area. http://med.stanford.edu/news/all-news/2020/04/testing-pooled-samples-to-trac

Stanford did a study looking for Coronavirus cases in Jan and Feb in the Bay area. http://med.stanford.edu/news/all-news/2020/04/testing-pooled-samples-to-track-early-spread-of-virus.html http://med.stanford.edu/news/all-news/2020/04/testing-pooled... > The researchers found that the burden of COVID-19 in the Bay Area prior to mid-February was low. Only two of nearly 3,000 people with respiratory-disease symptoms who were tested in early 2020 at Stanford Health Care or affiliated clinics for common respiratory viruses were infected with SARS-CoV-2, the virus that causes COVID-19.