Dr. O'Brien is the medical director of the Alta Bates Summit East Bay AIDS Center in Oakland, Calif., which provides primary and specialty medical care to more than 1,000 HIV-infected people, most of whom are indigent people of color. He is also an assistant clinical professor of medicine at the University of California-San Francisco.

After earning his undergraduate and medical degrees from the University of Washington-Seattle, Dr. O'Brien completed his internal medicine residency at the University of California-San Francisco. He is an accredited HIV specialist by the American Academy of HIV Medicine (AAHIVM), serves on the board of directors for AAHIVM's California chapter and is co-chair of the AAHIVM public policy committee. A published physician and periodic lecturer, Dr. O'Brien also acts as a consultant to the Alameda County Office of AIDS Administration, which oversees HIV prevention and care efforts for the East Bay portion of the San Francisco Bay Area, including Berkeley, Fremont and Oakland.