march 16: the "big seven" public health departments issued a joint shelter-in-place order, legally requiring all non-essential businesses to close and residents to stay at home except for essential needs, effective march 17. it was the first such order in the mainland united states, coming a day after puerto rico went into lockdown. march 17: the march 16 stay-at-home order is adopted by the remaining bay area county health departments. santa clara county has enforced its shelter-in-place order with one of the strictest interpretations in the state. the orders were timed to preempt saint patrick's day celebrations. march 30: the "big seven" health officers extend the shelter-in-place order to may 3, easing some restrictions on outdoor activity. april 13: sonoma county issues a mask mandate effective april 17. april 15: fremont issues a mask mandate effective immediately. april 17: santa clara county issues a mask advisory. the county refrained from issuing a mandate in order to avoid adding to police departments' enforcement responsibilities. april 22: mask mandates take effect in alameda, contra costa, marin, san francisco, and san mateo counties. april 24: mask mandates take effect in milpitas and cupertino. april 29: the shelter-in-place order is extended again to may 31. may 4: santa clara county issues a mask mandate for businesses. palo alto issued a face mask order on may 13. may 7: the big cities health coalition estimates that the bay area's shelter-in-place orders prevented 188,000 hospitalizations and 19,000 deaths in santa clara county, alameda county, and san francisco. may 14: san benito county meets the california department of public health's criteria to resume dine-in service at restaurants as part of phase 2 of governor gavin newsom's statewide reopening plan. may 15: san mateo county issues a new shelter-in-place order ahead of the bay area-wide order that expired on may 31. the county's order allowed nonessential retail and other businesses to offer curbside pickup service. this order, which aligned with phase 2 of the state reopening plan, marked the first departure from the unified front that bay area health officials had maintained until then. may 18: despite initial reservations by contra costa and santa clara county health officials, they and their counterparts in alameda county, berkeley, marin county, and san francisco issue a joint order on that implemented phase 2 reopening. napa, santa cruz, solano, and sonoma counties were also moving forward with phase 2. may 26: napa, san benito, solano, and sonoma counties begin allowing hair salons and barbershops to reopen. july 13: the san francisco zoo reopens to members with reservations required. july 14: university of california-berkeley botanical gardens reopens to members with reservations required. july 15: the san francisco zoo reopens to the general public with reservations required. july 22: university of california-berkeley botanical gardens reopens to the general public with reservations required. august 31: the statewide blueprint for a safer economy reopening plan comes into effect. napa and san francisco counties are at substantial, while all other bay area counties are at widespread. napa county directly follows the state's reopening guidelines. san francisco delays the reopening of businesses. september 1: san francisco allows personal care services and indoor malls to reopen. september 8: santa clara and santa cruz counties are upgraded from widespread to substantial. both counties directly follow the state's reopening guidelines. september 14: san francisco allows indoor nail salons, piercing shops, tattoo parlors, and indoor fitness/dance/yoga studios to reopen. september 15: marin county is upgraded from widespread to substantial. the county directly follows the state's reopening guidelines. september 21: san francisco allows museums/zoos/aquariums and elementary schools to reopen. elementary schools in san francisco unified school district remain closed. september 22: alameda, san mateo, and solano counties are upgraded from widespread to substantial. alameda county delays the reopening of businesses. san mateo and solano counties directly follow the state's reopening guildines. the de young museum reopens to members with reservations required. the de young observation level, coat check, de youngsters studio, and piazzoni murals room remain closed. september 25: the de young museum reopens to the general public with reservations required. the de young observation level, coat check, de youngsters studio, and piazzoni murals room remain closed. alameda county allows nail salons to reopen. nail salons have since been allowed to reopen statewide. september 29: san francisco county is upgraded from substantial to moderate. the reopening of businesses is delayed. contra costa county is upgraded from widespread to substantial. the county directly follows the state's reopening guidelines. september 30: san francisco allows indoor dining and places of worship to reopen. october 7: san francisco allows movie theaters to reopen without concessions. the national association of theatre owners of california/nevada stated that their cinemas in san francisco would remain closed due to the concessions ban, as it "makes it economically impossible for our members to reopen and significantly limits the moviegoing experience for our audiences." october 9: alameda county allows museums, zoos, aquariums, personal care services, libraries, fitness/dance/yoga studios, and outdoor film production to reopen. october 13: alameda and santa clara counties are upgraded from substantial to moderate. alameda county delays the reopening of businesses. santa clara county follows the state's guidelines, with the exception of allowing indoor restaurants to increase their capacity beyond 25%. san benito county is upgraded from widespread to substantial. the county directly follows the state's reopening guidelines. alameda county allows elementary schools to reopen. the california academy of sciences in golden gate park reopens to members with reservations required. exhibits and spaces with a high degree of interactivity or where it is difficult to maintain physical distance remain closed, including the morrison planetarium, the naturalist center, the curiosity grove, and the discovery tidepool. october 20: san francisco county is upgraded from moderate to minimal. the reopening of businesses is delayed. napa county is upgraded from substantial to moderate. the county directly follows the state's reopening guidelines. october 22: the california academy of sciences reopens to the general public with reservations required. exhibits and spaces with a high degree of interactivity or where it is difficult to maintain physical distance remain closed, including the morrison planetarium, the naturalist center, the curiosity grove, and the discovery tidepool. october 23: alameda county allows places of worship and cultural ceremonies, indoor dining, movie theaters, bowling alleys, and climbing walls to reopen. the county also allows indoor retailers and shopping centers to expand their capacity from 25% to 50% and fitness/dance/yoga studios to expand their capacity from 10% to 25%. october 26: schools in mountain house elementary school district reopen for grades tk–6. in-person attendance is only on monday through thursday. october 27: contra costa, marin, san mateo, and santa cruz counties are upgraded from substantial to moderate. all four counties directly follow the state's reopening guidelines. san francisco allows climbing walls and offices of non-essential businesses to reopen. the city also allows fitness/dance/yoga studios to expand their indoor capacity from 10% to 25%. november 3: san francisco allows swimming pools and bowling alleys to reopen. the city also allows places of worship, museums/zoos/aquariums, indoor dining, and movie theaters to expand their indoor capacity from 25% to 50%. november 9: alameda county allows middle schools and high schools to reopen. fremont christian school reopens for grades 3–5. november 10: contra costa and santa cruz counties are downgraded from moderate to substantial. november 16: alameda, napa, and santa clara counties are downgraded from moderate to widespread. san francisco county is downgraded from minimal to substantial. contra costa, san benito, santa cruz, and solano counties are downgraded from substantial to widespread. marin and san mateo counties are downgraded from moderate to substantial. november 28: san francisco and san mateo counties are downgraded from substantial to widespread. november 30: fremont christian school reopens for grades k–2. december 1: schools in piedmont unified school district reopen for grades k–2. december 6: 10:00 p.m.: contra costa, san francisco, and santa clara counties, as well as the city of berkeley, preemptively implement the state's december 3 regional stay-at-home order. 11:59 p.m.: the regional stay-at-home order goes into effect for the san joaquin valley region, which includes san benito county. december 7: alameda county preemptively implements the state's stay-at-home order. december 8: marin county preemptively implements the state's stay-at-home order. marin county is downgraded from substantial to widespread. schools in piedmont unified school district reopen for grades 3–5. december 16: san mateo becomes the final bay area county to ban outdoor dining december 17: 11:59 p.m.: the regional stay-at-home order goes into effect for the bay area region, which includes all abaho counties excluding san benito county. 2021 january 25: the regional stay-at-home order is lifted statewide. february 23: marin and san mateo become the first bay area counties since early december to leave the purple tier, being upgraded from widespread to substantial march 2: napa, san francisco, and santa clara upgraded from widespread to substantial march 9: alameda and solano upgraded from widespread to substantial march 13: contra costa and sonoma upgraded from widespread to substantial march 16: san mateo becomes the first bay area county since mid-november to enter the orange tier, being upgraded from substantial to moderate march 23: marin, san francisco, and santa clara upgraded from substantial to moderate march 30: alameda upgraded from substantial to moderate april 6: contra costa, napa, and sonoma upgraded from substantial to moderate may 4: san francisco upgraded from moderate to minimal may 11: san mateo upgraded from moderate to minimal may 19: santa clara upgraded from moderate to minimal june 1: solano upgraded from substantial to moderate june 8: alameda and napa upgraded from moderate to minimal june 15: bse system ended statewide. august 2: the counties of alameda, contra costa, marin, san francisco, san mateo, and santa clara (as well as the city of berkeley) re-introduce a mask mandate for all persons regardless of vaccination status. august 12: san francisco becomes the first major city in the u.s. to require proof of vaccination for customers of restaurants, bars, and gyms. september 2: berkeley announces that it will require proof of vaccination customers of restaurants, bars, and gyms. september 23: oakland unified school district announces a vaccine mandate for all students aged 12+. september 29: santa cruz county lifts its indoor mask mandate, effective immediately. october 7: san francisco announces that it will lift its mask mandate, effective october 15, for gatherings of under 100 people where everyone is vaccinated. october 8: marin county announces the same modifications to its mask mandate as san francisco, also effective october 15. october 13: san francisco begins mandating vaccination for workers of restaurants, bars, and gyms. october 30: marin county announces an end to its indoor mask mandate, effective november 1. 2022 january 12: sonoma county institutes a 30-day ban on indoor gatherings of more than 50 people and outdoor gatherings of more than 100 people. january 27: san francisco announces that it will lift its indoor mask mandate if everyone has received a booster dose of the vaccine, effective february 1. february 20: point bonita lighthouse, located in the marin headlands near sausalito, resumes tours for the first time after two years of closure due to the covid-19 pandemic. military response california national guard staff set up a federal medical station at the san mateo county event center. the california national guard and california state guard activated medical units in the bay area to assist local and state government agencies in their covid-19 response. in the bay area, the california air national guard has set up federal medical stations at the santa clara convention center in santa clara (known as the field respite center), the san mateo county event center in san mateo, and craneway pavilion in richmond. the temporary field hospitals, which are managed by the strategic national stockpile division of the united states department of health and human services, can receive noncritical patients from local hospitals for convalescent care. the santa clara location was converted on march 21 and admitted its first two patients on april 5. the air national guard converted the san mateo location on april 1 and the richmond location the following day. community and academic response the innovative genomics institute at the university of california, berkeley, headed by dr. jennifer doudna converted the genomic-editing research laboratory to run covid-19 tests. despite a widespread need