As COVID-19 cases surge, San Francisco and other Bay Area communities moved this week to expand mask requirements to all gyms, offices and other indoor settings that previously had been exempt.San Francisco city officials announced Wednesday that starting on Thursday, masks will once again be required for settings with stable populations of fully vaccinated people, including gyms, religious gatherings and workspaces. The city and other highly vaccinated Bay Area counties had previously been exempted from the state’s mask mandate for stable settings of vaccinated groups of 100 or fewer.“We know that our focus in this Omicron surge must be on reducing hospitalizations and maintaining our capacity to care for San Franciscans, and these measures will help ensure this,” said San Francisco Health Officer Dr. Susan Philip. “We do not want to wait until it’s too late to implement these measures to better protect our community.” The move comes a day after the San Francisco Department of Emergency Management announced the city was nixing its New Year’s Eve fireworks show, tweeting that “the decision to cancel is a proactive measure that will best protect SF & essential front-line workers.”San Francisco is one of several Bay Area communities dropping their exceptions to mask mandates. Marin, Alameda, Sonoma and Contra Costa Counties and the city of Berkeley are also doing so. “The Omicron variant is very contagious, and we now know that anyone, regardless of vaccination status, can spread this variant to other people,” said Dr. Ori Tzvieli, Contra Costa County deputy health officer. “We anticipate the case rate and hospitalization numbers to increase over the coming weeks.” The first case of the Omicron variant, a highly contagious mutation of the virus that now comprises the majority of new cases in the United States, was detected in Sonoma County on Dec. 16. Since then, the rate of new daily COVID cases has increased 15% in Sonoma County.Nearly 80 cases a day are being detected in Sonoma County among people who are fully vaccinated, an all-time high. Sonoma County health officials are aware of at least two COVID outbreaks following holiday parties where stable cohorts of fully vaccinated people gathered indoors without wearing masks, resulting in nearly 40 known positive cases to date.While breakthrough cases in vaccinated people are rising, unvaccinated people are exposed to the greatest risks. The number of COVID-19 cases detected daily in unvaccinated people in Sonoma County has more than tripled since Thanksgiving, from 16.9 per 100,000 residents to 51.9 per 100,000 residents, the highest since late August. New daily cases detected among vaccinated residents increased from 6.9 per 100,000 residents to 7.9 per 100,000 residents during the same period.San Francisco’s seven-day average case rate has surpassed the peak average during the summer’s Delta surge and continues to grow. “Cases are rising three times faster than during the summer Delta-fueled surge and further rapid increases are expected,” city officials said in a written statement Wednesday. “While the hospitals currently still have ample capacity, the rate of hospitalizations has also started to increase but so far remains low compared to last winter.”In Contra Costa, the average number of daily new COVID-19 cases has risen 149% over the last week and hospitalizations have grown by 31%.San Francisco also will require expanded vaccination verification starting Feb. 1 for indoor events of 1,000 people are more. Patrons will have to show they have been boosted, as well as vaccinated. Those between ages 5 and 11 must show vaccination or a negative COVID-19 test result and children 2 to 4 also will need a negative test result to enter.The city’s return to mask mandates for fitness centers and other 100% vaccinated settings will be enforced until Jan. 31.San Francisco had the first detected case of Omicron in the country, announcing its presence on Dec. 1 in a vaccinated person who had recently returned from a trip to South Africa. Two weeks later, city officials said that at least 30 probable cases of Omicron had been detected. That number rapidly grew. Between Dec. 17-20, the variant accounted for nearly 4 of every 5 coronavirus infections.Since Omicron was first detected in Sonoma County on Dec. 16, the rate of new daily cases has risen by 15%. Although the unvaccinated are most at risk, breakthrough cases are not uncommon. County officials said that nearly 80 new cases in vaccinated people are being reported each day, an all-time high.“The vaccine works,” said Sonoma County Health Officer Dr. Sundari Mase. “It greatly reduces the chances you will become severely ill or die if you contract the virus, but it won’t stop you from infecting others. If they are immunocompromised or unvaccinated, they could require hospitalization and even die.”