Dr. Eva Harris, a public health professor specializing in infectious diseases and vaccinology and Dr. Lisa Barcellos, a public health professor specializing in epidemiology and biostatistics, are co-leading an extensive study of the Bay Area's exposure to the virus to see how widespread it has been and for how long. On this program, they discuss their strategy, which includes a mailed questionnaire, followed up with testing. Dr. Harris says they've mailed 307,000 invitations to participate in the study to "every single home, every household in the census track in 11 cities." Dr. Barcellos says: "We're asking all about current symptoms, past symptoms and going back as far as December. We're asking about travel histories. We're asking about who's in the household and what they've been exposed to." From the respondents, 5,000 to 6,000 will be selected randomly to participate in the testing phase. "The in-home collection kits include all the materials that someone needs to collect saliva, as well as an oral and nasal swab," Dr. Barcellos says. "It's really very straightforward and doesn't hurt at all," Dr. Harris adds. Link to video. Read more about the study at Berkeley's School of Public Health.