Los Angeles County reported more than 20,000 new coronavirus cases Thursday — the latest eye-popping total as a wave of infections fueled in part by the highly transmissible Omicron variant washes over the region.“We are, in fact, experiencing the worst of a surge at the moment with the rising number of cases,” county Public Health Director Barbara Ferrer told reporters.Thursday’s reported total, 20,198, is one of the highest ever seen in the pandemic. Over just the last two days, the nation’s most populous county has announced nearly 37,000 new cases. L.A. County is far from alone in contending with a new crush of infections. Overall, California’s reported average daily coronavirus caseload has more than quadrupled in the last two weeks — an astonishing rise that has pushed infection levels significantly higher than at any point during the summer surge.Despite the ballooning infections, far fewer COVID-19 patients are hospitalized now than during either of the pandemic’s last two waves, and health officials appear increasingly optimistic that symptoms in cases linked to the rapidly proliferating Omicron variant may be less severe than seen with other versions of the coronavirus. But the recent near-vertical trendline nonetheless underscores the rampant spread of the coronavirus, and has prompted increasingly urgent calls for caution from health officials who worry that hospitals may still be slammed by a new crush of patients if transmission remains this high.“Throughout the pandemic, first we see a rise in cases and a bit later we see a rise in hospitalizations and a bit after that we see a bump in deaths from COVID,” said Dr. Sara Cody, the public health director and health officer for Santa Clara County. “So, while we don’t yet know exactly how the severity of Omicron compares with the severity to other variants … our case rates are going up incredibly fast, and some proportion of people that get sick will require a hospital bed.”Over the weeklong period ending Wednesday, California announced an average of 23,637 new coronavirus cases per day, according to data compiled by The Times. During the week ending Dec. 15, the average was 5,792 per day. The summertime spike peaked at a bit more than 15,000 new cases per day. During the worst days of last winter, however, the daily average case count was closer to 45,000.Officials say the latest wave is likely fueled by a few factors, including increased travel and gatherings for the winter holiday season and breakneck proliferation of Omicron — which has mushroomed rapidly statewide since its presence was first confirmed at the start of the month.