An outbreak of the new coronavirus at San Francisco’s largest homeless shelter has infected 70 people, the city’s mayor announced Friday. London Breed said MSC South found its first positive case Sunday and has since moved infected individuals—68 shelter occupants and two staff—into hotels for quarantine to prevent infections. Public health officials said they were in the process of testing all the shelter’s occupants. Because of the impossibility of avoiding contact with other people while homeless, experts have warned that people living on the streets would be especially vulnerable to COVID-19. The California state government has procured 7,000 hotel rooms to house the homeless and slow the spread of the virus among them.