Los Angeles County is experiencing a “staggeringly fast rise” in newly confirmed coronavirus cases, with more than 6,500 additional infections reported Wednesday alone, according to a top health official. The latest caseload, 6,509, is more than double the total reported Tuesday.The countywide positivity rate for those who seek testing, a key metric of coronavirus transmission, has also jumped dramatically — to 4.5%, up from 1.9% a week ago. “These numbers make it crystal clear that we’re headed into a very challenging time over the holiday,” county Public Health Director Barbara Ferrer told reporters. “If our case numbers continue to increase at a rapid pace over this week and next, we could be looking at case numbers we have never seen before.”The massive jump in cases, Ferrer said, reflects increased circulation of the Omicron variant, which has spread rapidly since its presence was first confirmed in California three weeks ago.“The reality is that the vast majority of folks testing positive today are infected with Omicron, a more easily transmitted strain of the virus,” Ferrer said. She added, though, that it’s unvaccinated residents who remain particularly exposed to the worst effects of COVID-19. From Dec. 5 to 11, unvaccinated Angelenos were five times likelier to get infected, 21 times more likely to require hospitalization and 18 times likelier to die. L.A. County has a relatively high overall level of protection — with more than 75% of residents having already gotten at least one shot and about 68% being fully vaccinated. However, there are still roughly 2.2 million eligible Angelenos who have yet to receive their first dose.That “is a large number and can really, unfortunately, create a lot of heartache, both for families and for our hospitals,” Ferrer said.So far, COVID-19 hospitalizations have not yet spiked to the same alarming degree as cases. But the number of coronavirus-positive patients countywide is rising. The county’s daily patient census on Tuesday — 770 — represents a 35% increase since the start of the month. More concerning still is that it typically takes about two weeks for increases in case counts to trigger corresponding spikes in the number of people requiring professional healthcare. In other words, the recent rise in hospitalizations doesn’t yet reflect the massive rise in cases. “This staggeringly fast rise, and the healthcare system strain that has followed similarly steep increases elsewhere in the world, is the cause of our alarm,” Ferrer said.Officials in L.A. County and across the state have long said they expected some sort of resurgence in coronavirus transmission heading into the winter, when falling temperatures would increasingly push gatherings into riskier indoor settings and the busy holiday calendar would tempt more people to travel. The emergence of the highly mutated Omicron variant has only heightened those fears, given how readily it is now spreading. There have been some optimistic indications that Omicron, despite its infectivity, may cause milder disease than some of the earlier variants.While “we’d be really grateful if, in fact, evidence continues to mount that Omicron causes less severe illness,” Ferrer said there’s still a “numbers problem.” “If Omicron causes less severe illness, but it infects many more people, then even if you had a smaller number of the people who are infected get severe illness, you could still end up with overwhelming numbers,” she said.A surge of any scale also will further stress the county’s beleaguered healthcare system, which has now been on the front lines of the pandemic for nearly two years. Although facilities may have beds and supplies available, the human stress — in terms of illness, stress and overwork among staff — has undoubtedly taken a toll.It’s important to recognize “that we’re talking about a healthcare system that is already just horrifically fatigued,” said Holly Mitchell, chair of the L.A. County Board of Supervisors. “To continue to kind of push the envelope and expect that they will just stand and deliver and think that they have the same capacity, the human capacity, that they did a year ago or 18 months ago just isn’t realistic,” she said. Despite the alarming rise in cases, Ferrer said she doesn’t think conditions call for new restrictions.Rather, officials say upticks in transmission should be cause to double down on measures already in place — such as wearing masks in indoor public settings — and provide further evidence of the benefits of getting vaccinated and boosted. “I do not, at this point, anticipate that we move into a lot more restrictions across the board,” Ferrer said. “I don’t think it’s necessary right now because we do have these new tools that we didn’t have last year.”But, she added, “every single option has to be on the table. Every single tool we have needs to be available for us to protect people’s lives and livelihoods and to, in this case, avoid overwhelming the hospital care system.”The threat posed by Omicron may have already prompted some people to scale back or call off their holiday plans. And given that transmission is increasing, Ferrer said “this is a time for everyone to be really cautious and … reassess what you’re planning to do based on your risk, the risk of the people you love and what’s absolutely essential.”But she reiterated she thinks there are ways for people to celebrate safely. “I don’t want people to think that we are recommending that nobody do anything for the holidays,” she said. “For those who are fully vaxxed, fully boosted, you’re able to get tested before your gatherings, you’re opening windows and doors if you’re going to need to be inside and you’re fully ventilating, you’re keeping your gatherings relatively small, I think you can go ahead and feel relatively safe again.”