Quick Take:

Cases are expected to spike, but holiday gatherings can be safe, even without masks, if everyone is vaccinated and boosted, Fauci says.

The Omicron variant of the coronavirus is now spreading rapidly across California, fueling big upticks in infections across the state.

At least three California health systems have reported that Omicron appears to account for 50% to 70% of new cases, state health officials said Thursday, and clinical and wastewater data suggest Omicron is now spreading in most parts of California.

However, the full scope of this latest wave remains to be seen.

Cases are expected to spike, perhaps to unprecedented levels. Some hospitals are likely to again come under stress from a renewed influx of COVID-19 patients.

But for now, officials say they can contend with the surge by doubling down on common-sense safety practices and promoting vaccinations and booster shots, rather than resorting to new lockdown orders.

Los Angeles County provided a glimpse of what may be to come. A day after reporting 6,509 new coronavirus cases — which was more than twice the figure from the day before — county health officials reported an even higher infection total Thursday: 8,633.

“These numbers make it crystal clear that we’re headed into a very challenging time over the holiday,” county Public Health Director Barbara Ferrer said. “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.”

What will the next few weeks look like?

As Omicron is still a relatively new arrival — its presence was first confirmed in California just three weeks ago — there are many unanswered questions as to what its impact will be.

One thing that seems certain, though, is that the variant can spread rapidly. Already, Omicron now constitutes 73% of the nation’s coronavirus cases, up from 13% the week before, according to federal estimates.

The U.S. Centers for Disease Control and Prevention say early forecasts suggest a large surge of infections could be reached by early January, and “the peak daily number of new infections could exceed previous peaks.”

“This rapid increase in the proportion of Omicron circulating around the country is similar to what we’ve seen around the world,” CDC Director Dr. Rochelle Walensky said during a briefing. “Although this is a reminder of [the] continued threat of COVID-19 variants, this increase in Omicron proportion is what we anticipated and what we have been preparing for.”

Dr. Anthony Fauci, President Biden’s chief medical adviser, said in an interview on ABC that during this wave, almost everyone is “either going to get infected, particularly the unvaccinated, or be vaccinated.”

“And the vaccinated people, particularly the boosted people … will either be protected from infection, or if they do get infected, they’ll have a relatively mild course of infection,” said Fauci, who expected a peak in Omicron cases soon, within a matter of weeks, followed by “just as dramatic a decline.”

In various television interviews, Fauci has said that family and friends can expect relatively safe and enjoyable Christmas gatherings — without masks — if everyone 5 and older is vaccinated and has received a booster shot if eligible. He also suggested attendees get tested before gathering.

“If tests are available, by all means go the extra step, go the extra mile to get testing, which we’re recommending just to get that extra added cushion of alleviation of concern,” Fauci told NBC.

But, he added, “if you don’t have the availability of the test and you are fully vaccinated and boosted, you should feel comfortable having a holiday meal or gathering with family members who are also vaccinated and boosted.”

One thing appears clear: Omicron will become dominant, and many people will get infected.

A highly influential COVID-19 forecast is projecting that the Omicron surge may result in as many as 400,000 new coronavirus cases a day across the nation — significantly higher than last winter’s record of 250,000 cases a day.

The University of Washington’s Institute for Health Metrics and Evaluation projects that the Omicron surge will continue rising swiftly through December and into January, potentially peaking later next month or in early February. Despite the increase in cases, predictions indicate there will be fewer daily deaths than during last winter’s devastating peak.

The institute also predicts that single-day COVID-19 deaths could climb as high as 2,000 nationally by early February, about the same number reported during the Delta surge but fewer than the nearly 3,500 daily deaths during last winter’s peak.

The forecast for California projects as many as 150 COVID-19 deaths a day by the end of February, a rate similar to the peak of the summer Delta wave. Still, that is far fewer than last winter’s surge, when California was tallying 550 deaths a day.

What are California officials doing?

Seven UC campuses have delayed in-person return to campus, and all UC and Cal State campuses will require boosters for eligible students. The state has also announced that healthcare workers will be required to get COVID-19 vaccine boosters in hopes of protecting both the medical community and the vulnerable populations they serve.

Some cities are taking their own preemptive steps. This week, Oakland moved to join Los Angeles, San Francisco, West Hollywood and Berkeley in requiring proof of vaccination to patronize indoor restaurants and gyms. And in San Jose, the mayor has said he wants to require all city employees to receive booster shots as a condition of employment and anyone who enters city-owned facilities to do the same.

California is also preparing to provide rapid tests for students in K-12 public schools and expand hours at busy screening sites.

“After our kids have enjoyed the holidays … we want to make sure they come back in as good a shape as they left, meaning we want to make sure that we are testing our kids and preparing them to come back,” said Gov. Gavin Newsom.

Newsom emphasized California’s commitment to keeping schools open for in-person instruction — a pledge reiterated in a joint statement his office released Wednesday morning from education-related organizations including the California State Parent Teacher Assn., California Teachers Assn., SEIU California, the state charter schools association and the California School Boards Assn.

Who is most at risk?

Experts say being vaccinated and boosted continues to provide strong protection, especially when it comes to severe disease.

The big fear is for the unvaccinated.

Unvaccinated people are at highest risk of severe illness from any coronavirus infection. The first apparently publicly confirmed Omicron case in the U.S. that has resulted in a death was reported in Harris County, Texas — a man in his 50s who was unvaccinated, had previously survived a coronavirus infection, and had underlying health conditions that placed him at higher risk of severe complications.

“Due to Omicron, we expect a significant rise in cases,” said Jeff Zients, Biden’s COVID-19 task force coordinator. “Fully vaccinated people, particularly those with a boost, are highly protected. But due to Omicron’s highly transmissible nature, we will see fully vaccinated people get COVID. They’ll likely be asymptomatic or feel under the weather for a few days. Let’s be clear: Unvaccinated people are at a higher risk of getting severely ill from COVID, getting hospitalized and dying.”

The CDC has warned that hospitals could be further burdened with many healthcare workers forced to isolate due to their own coronavirus infections, as well as illnesses from other causes, such as flu.

In Los Angeles County, 68% of residents of all ages are fully vaccinated, according to data compiled by The Times. In San Francisco, that share is 81%.

The San Francisco Bay Area has some of the highest vaccination rates in state, and officials there believe that could help slow Omicron. But experts remain especially nervous about places with low vaccination rates, such as the Inland Empire and San Joaquin Valley.

One possibility is that the Bay Area will see a relatively small jump in hospitalizations; L.A. County, a medium jump and the Central Valley the highest jump, said Dr. Peter Chin-Hong, an infectious diseases expert at UC San Francisco.

That pattern would be similar to this year’s Delta surge, where the San Joaquin Valley’s peak summer hospitalization rate was twice as worse as Southern California’s and nearly three times as bad as the Bay Area’s. The San Joaquin Valley’s hospitals have been overwhelmed since the Delta surge began; the Bay Area’s hospitals have not sounded similar alarms.

How should we be looking at the numbers?

The consensus seems to be that cases will continue to rise, perhaps dramatically.

In the coming days, COVID-19 hospitalizations will be a more relevant way to determine actions that local authorities may need to take, said Ali Mokdad, a professor of health metrics sciences at the Institute for Health Metrics and Evaluation.

That’s because, while Omicron is rapidly spreading, there also will be a relatively high percentage of people infected with the variant who will remain asymptomatic, and a lower percentage of newly infected people who will require hospitalization.

In California, a hopeful scenario would be if Omicron’s disease severity is half of Delta’s and the state can double its booster uptake, raise its vaccination rate to 80% and lower the number of residents’ close contacts for the next month. That would result in a statewide winter peak of 10,000 COVID-19 patients by late January — about half last winter’s surge and 20% worse than the summer Delta wave.

“Although 10,000 hospitalizations … across the state are far more than we ever want to see, it is more manageable than the alternatives,” Ferrer said. “Realistically, to avoid the worst of the scenarios, we need to work right now to increase vaccinations and booster uptake.”

As of Wednesday, 3,622 COVID-19 positive patients were hospitalized statewide. That’s up about 6.5% from two weeks ago.

Does Omicron cause less severe COVID-19 than Delta?

There are some hints of optimism among early data from England, Scotland, Denmark and South Africa, which suggested that an Omicron infection resulted in a 40% to 70% reduced need for hospitalization compared with the Delta variant.

There’s also no evidence that people who are vaccinated and have received a booster shot are getting severely ill with Omicron, unless they have a significantly weakened immune system.

That raises the possibility that this winter in the U.S. won’t be as deadly as last year’s devastating surge.

“However, we must wait to see what happens in our own population, which has its own demographic considerations,” Fauci said.

The U.S. also has other challenges, with a lower rate of vaccination than Britain or Denmark. But while hospitals in Denmark and South Africa are not being overwhelmed, the healthcare system “is having a tough time in England — because they were already working so hard with Delta, kind of like parts of our country,” said Dr. Eric Topol, director of the Scripps Research Translational Institute in La Jolla.

What about hospitals?

The biggest worry is that Omicron could spread so fast that some hospitals could still be overwhelmed. The ultra-contagious nature of Omicron means that an extraordinarily high number of people could get infected simultaneously.

Even if a lower percentage of them need hospital care, if there are so many more people who are suddenly infected, that could result in strained hospital systems and, in some areas, overwhelm them, especially in areas with low vaccination rates.

“If you have a much larger number of individual cases, the fact that you have so many more cases might actually obviate the effect of it being less severe,” Fauci said.

This story originally appeared in Los Angeles Times.