November 27, 2020 7:59 am COVID-19 Immunity: How Long Do Antibodies Last? COVID-19 patients develop a certain level of immunity after battling the virus, but new studies find it may not last long. 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