A likely deluge of new COVID cases is on the horizon for the Bay Area, due to the Omicron variant and despite widespread vaccination. Booster shots seem to provide some protection, but not complete protection — and you should be on alert for some specific new symptoms being reported.

It remains to be seen whether we will come out of a likely winter surge with overflowing ICUs or not — and the severity of Omicron coupled with relatively high vaccinations around the Bay point to a likely much less dramatic winter than we saw in local hospitals last year. But it is looking more and more clear that surge is happening — and experts continue to warn that milder cases on average don't matter if the variant is many times more transmissible than Delta, meaning that the two factors could cancel each other out and hospitalizations will still rise.

San Francisco health officials announced Friday that they've confirmed 31 cases of the Omicron variant in the city, but there are likely many going undetected by official testing channels.

Three of those cases are in the Mission District, and as ABC 7 reports, none of those three cases involved any type of travel.

"It wasn't like they just got off a plane from South Africa or somewhere else," says Dr. Joe DeRisi, professor of biochemistry and biophysics at UCSF and co-president of Chan Zuckerberg Biohub, speaking to ABC 7. "Meaning that there must be unseen community spread of that virus that we are not yet detecting [in the city]."

It's been three weeks since the first Omicron case in the country was confirmed in San Francisco on December 1, in a traveler recently returned from South Africa. But very quickly, as more samples were being sequenced across the country, more cases with earlier transmission dates were found in New York and elsewhere, indicating that community spread had begun on the East Coast even earlier.

Many restaurants, events, and Broadway shows in New York City have temporarily shut down this week as the variant appears to be spreading like wildfire there — and Saturday Night Live made the unusual decision, just hours before air time on Saturday, to send most of the cast and crew home and to put on an altered show with no audience, but with host Paul Rudd and guests Tina Fey and Tom Hanks, who had both already committed to appearing.

In San Francisco, AL's Place in the Mission was shuttered over the weekend, saying in an Instagram post that this was "to ensure the safety and well being of our guests and staff alike." Suggesting that perhaps there had been some symptoms or some specific reason for the closure, the restaurant said, "We are spending this weekend for quarantining, testing, and making sure our employees are in good health!" AL's Place says it will reopen on Wednesday, December 22.

As the Chronicle reports, Hi Felicia Supper Club in Oakland shut down temporarily due to positive cases on the restaurant's staff, as did Bar Shiru and Tacos Oscar. Friends and Family Bar, also in Oakland, temporarily closed until after Christmas due to an "increased number of potential staff exposures."

UCSF's Dr. Bob Wachter said in a Twitter thread Friday, "We have far more clarity now than we had 3 wks ago, but many unknowns remain" about the Omicron variant and the current picture.

Wachter warns of a coming deluge of cases due to the new variant, and he says, "I see the next few months as a time to fortify one's safety behaviors." He says that things are much more "nuanced" now than they were last winter, with so many people vaccinated and boosted, and a healthy 30-year-old probably only needs to work about the risks of unwittingly spreading to virus to someone more vulnerable.

He says that people with three shots of either the Pfizer or Moderna vaccine should consider themselves "very immune," and those who are boosted and who were also previously infected are now "super-immune." But there will be gradations down from there and there will continue to be mild breakthrough infections that still seed other infections. And risk factors now need to be weighed against the importance of certain activities to you — and going into crowded spaces will be a calculated risk for the next couple of months.

And Wachter said he'd spoken with a friend in New York City who had COVID in 2020, and had three mRNA vaccine shots, but after attending holiday parties last week where proof of vaccination was required, the friend is once again COVID-positive. "It's a different foe," Wachter said of the variant. "Treat it [with] respect."

Dr. Peter Chin-Hong of UCSF suggests to KPIX, "It’s probably going to hit early in 2022 in the Bay Area if not sooner in terms of large numbers of people, [and] it’s already here of course and it’s widespread in California."

Whether or not this holds true with Omicron remains to be seen, but a new, huge study has concluded that 40% of COVID cases — broadly speaking — are asymptomatic. That means that asymptomatic spread has likely always been a major factor in this pandemic, even moreso than was previously believed.

Also: Omicron has a new symptom profile, and it looks like the loss of taste and smell is less common with this variant. More common symptoms to look for now: scratchy throat, lower back pain, nasal congestion, and dry cough. Symptoms with Omicron seem to appear within two to three days of exposure, so even faster than the Delta variant, which was already faster than the original variant.

Related: San Francisco Might Have at Least 30 Unconfirmed Omicron Cases

Photo: Anastasiia Chepinska