The Bay Area, which consists of nine counties and nearly 8 million people, is a cautionary tale for government and health officials. Even though leaders here tried to do everything cautiously and by the book, cases still eventually spiked over a month and a half, to an average of 877 cases a day at the end of July from 217 a day in mid-June.

Medical experts say a slow but steady rise in complacency is worsening the case count. Contact tracers have told public health researchers that people are getting sick after indoor gatherings. And the numbers show that Latino residents and essential workers are being hit the hardest.

Many people who live here say they are worn out – that a hermitlike existence is impossible for months on end. Tired of being stuck at home, friends and families are starting to gather again, and some parents are letting their children use still-closed playgrounds, ducking under the caution tape that has been wrapped around jungle gyms since March.