The true number of COVID-19 cases in California’s Silicon Valley is at least 50 times higher than the official figure, according to a preliminary study that took blood samples from a group of residents and tested them for viral antibodies. Stanford researchers used Facebook to recruit 3,300 volunteers from Santa Clara County and estimated that between 2.5 to 4.1 percent of the population had been infected, which is 50 to 85 times higher than the number of confirmed cases.
