coronavirus June 4, 2021 5:12 pm UCSF Doctor Discusses COVID Vaccines, Breakthrough Cases UCSF infectious disease specialist Dr. Peter Chin-Hong joins Janelle Wang to discuss breakthrough coronavirus cases in fully vaccinated people. US & World Videos 2:19 San Francisco barbershop struggles to stay open after pandemic 0:51 Alameda County using dogs to detect COVID 3:57 Interview: Doctor's perspective on COVID 4 years after shutdown started 2:27 Marking 4 years since COVID-19 shut down the Bay Area 2:09 CDC updates COVID isolation guidelines