After about a month since the omicron COVID-19 variant was detected in South Africa and two weeks since first recorded in the U.S., scientists and health officials have been working to combat the mutated virus with new information.
So, what do we know about the new variant and its impact on Illinois?
Here's a breakdown of what we know so far.
What do we know about Illinois' first omicron case?
Omicron was reported in a fully vaccinated city resident who had also received a booster dose but was visited by an out-of-state traveler who also tested positive for the variant. The resident did not require hospitalization, is improving and has been self-isolating since their symptoms began, officials said.
“While unsurprising, this news should remind Chicagoans of the ongoing threat from COVID-19, especially as families prepare to come together over the holidays,” Chicago Department of Public Health Commissioner Dr. Allison Arwady said in a statement. “We know how to slow the spread of this virus: get vaccinated, get boosted, get tested if you have symptoms or have been in contact with someone with COVID-19, and stay away from others if you test positive. Wear a mask indoors, avoid poorly ventilated spaces, practice social distancing, and wash your hands.”
Health officials had been preparing for the variant to be detected in both the city and state this week.
Arwady said earlier in the day that test results are currently pending for city residents who are known contacts of out-of-state or out-of-country omicron variant cases.
"We are following multiple individuals who we know had exposures, whether they were traveling in the U.S. or even internationally, and we have a pretty robust way to share information in a way to protect privacy, but allow us to do case investigation or contact tracing, including over state boundaries," she said.
In a Facebook Live Tuesday, Arwady said the city has had a plan in place for once the variant was identified.
How widespread is the omicron variant?
The omicron COVID variant first detected in southern Africa about a month ago now makes up about 3% of cases sequenced in the U.S., according to data from the CDC.
More than two dozen states have reported omicron cases so far. California was first to confirm an omicron case in the U.S. on Dec. 1 in a resident who flew into San Francisco from South Africa. But the CDC on Friday said they've confirmed an earlier case of omicron in a patient who developed symptoms on Nov. 15. It's not clear when the variant first arrived in the U.S.
Minnesota recorded the first Midwest case of the omicron COVID variant via a specimen from a resident "with recent travel history to New York City," health officials said.
Wisconsin also recorded its first case of the highly mutated omicron COVID variant in a resident who, according to the health department, recently traveled to South Africa.
Is Chicago taking any precautionary measures in light of the newly detected variant?
Arwady said the city plans to continue pushing for residents to get vaccinated against COVID-19 and get their booster shots as soon as they are eligible, meaning six months after Moderna or Pfizer's vaccine or two months after the Johnson & Johnson vaccine.
"We are still learning. Lots of you are asking, 'Are we going to need an omicron booster? We might," Arwady said. "We’ll know in another two weeks or so once all the data has been collected related to how well not just has the vaccine been protecting around the world, but has the booster been protecting. How well has 'natural immunity,' been protecting? Because we've been seeing a lot of folks who were kind of counting on prior infection getting infected again with this omicron variant in other parts of the world. And so I don't have the answers out of whether an omicron booster will be needed, but what I do know is that getting the vaccines we have now and getting boosted has helped protect against the spread of omicron in a number of case examples."
Masks will continue to be required indoors, Arwady said, and testing availability will be increased. City employees will be encouraged to stay home if they are sick, though vaccine requirements will likely continue and Chicago may begin requiring proof of vaccination for certain public spaces or activities, Arwady said.
"I'm more interested in that than I am in needing to, you know, do some of the major shutdowns and theaters and many other places have already been doing this but it is certainly something that if, you know, as this increase is continuing and perhaps with the new variant we may do more of."
Has anyone died from the omicron variant?
The CDC on Friday said one vaccinated person has been hospitalized with omicron, but no deaths have been reported among the 43 patients that have been followed up on.
Among those patients, 58% were between the ages of 18 and 39 years of age and 79% were fully vaccinated at least 14 days before symptom onset or testing positive.
The CDC reported that 33% of the 43 patients traveled internationally during the 14 days prior to developing symptoms or testing positive, indicating that community spread is underway in the U.S.
What are the symptoms of omicron?
COVID symptoms linked to the omicron variant have been described as "extremely mild" by the South African doctor who first raised the alarm over the new strain. CDC data showed the most common symptoms so far are cough, fatigue, congestion and a runny nose.
Dr. Angelique Coetzee, chair of the South African Medical Association, told the BBC that she started to see patients around Nov.18 presenting with "unusual symptoms" that differed slightly to those associated with the delta variant, which is the most virulent strain of the virus to date and globally dominant.
"It actually started with a male patient who's around the age of 33 ... and he said to me that he's just [been] extremely tired for the past few days and he's got these body aches and pains with a bit of a headache," she told the BBC.
The patient didn't have a sore throat, she said, but more of a "scratchy throat" but no cough or loss of taste or smell — symptoms that have been associated with previous strains of the coronavirus.
Coetzee said she tested the male patient for COVID, and he was positive, as was his family, and then said she saw more patients that day presenting with the same kinds of symptoms that differed from the delta variant.
Other patients she had seen so far with the omicron variant had also experienced what she described as "extremely mild" symptoms, and she added that her colleagues had noted similar cases.
"What we are seeing clinically in South Africa — and remember I'm at the epicenter of this where I'm practicing — is extremely mild, for us [these are] mild cases. We haven't admitted anyone, I've spoken to other colleagues of mine and they give the same picture."
Similarly, in the U.S. case, Fauci said the person was vaccinated but had not received a booster shot and was experiencing “mild symptoms.”
But Moderna CEO Stephane Bancel told CNBC on Monday that omicron symptoms reported in South Africa may not be a good predictor of the variant's virulence in other parts of the world, because the country has a much younger and healthier population than European nations and the United States.
"The trick is you're not going to be able to tell the difference between omicron, delta lambda, plain COVID from the beginning," Landon said. "Influenza or even common rhinovirus causes most of our common colds in the winter. You're not going to know the difference between those if you just look at your symptoms. For many people, those symptoms are overlapping. And while there are some parts of the Venn diagram like taste, loss of taste and smell, or common COVID than these other things, there's a lot of overlap. You're just not going to know especially at the beginning of an illness, what kind of illness you have. You have to get tested."
But getting tested won't necessarily tell you if you have the omicron variant, Landon said.
"When you get a COVID test they're just looking for whether or not you have COVID," she said. "They're not on which kind of in order to figure out the exact strain of COVID. You have to do this thing called sequencing, which takes a lot longer. It's much more intensive. You certainly can't get that back in 24 hours, and it's only done by specialized labs."
What about vaccines and prevention of the new variant?
Last month, the Centers for Disease Control and Prevention cleared the way for all adults to get a COVID-19 booster shot, if they want one. But now, with the emergence of the new omicron variant, the CDC is intensifying that message — saying those over 18 years old should get one.
"Everyone ages 18 and older should get a booster shot ... when they are six months after their initial Pfizer or Moderna series," CDC Director Dr. Rochelle Walensky said in a statement Monday.
"The recent emergence of the omicron variant (B.1.1.529) further emphasizes the importance of vaccination, boosters, and prevention efforts needed to protect against COVID-19," she added.
Similarly, Chicago health officials urged residents to get their booster shots or get vaccinated if not already.
"I want people to get a booster now," Arwady said. "Why do I want people to get a booster now? Because right now -- forget omicron -- delta [variant] is doing a job on Chicago and on the upper Midwest."
Moderna's Chief Medical Officer Paul Burton said the vaccine maker could roll out a reformulated vaccine against the omicron coronavirus variant early next year.
The vaccine maker "mobilized hundreds" of workers starting early Thursday morning, on Thanksgiving, to start studying the new variant, the company said in a statement.
Current vaccines could provide some protection, depending on how long ago a person was injected, Burton said. Still, he said unvaccinated people should get vaccinated or receive their booster shots, if eligible.
It's not clear whether new formulations will be needed, or if current COVID vaccinations will provide protection against the new variant that has begun to spread around the globe.
"We should know about the ability of the current vaccine to provide protection in the next couple of weeks, but the remarkable thing about the mRNA vaccines, Moderna platform is that we can move very fast," Burton said on BBC's "Andrew Marr Show."
"If we have to make a brand new vaccine I think that's going to be early 2022 before that's really going to be available in large quantities," the Moderna chief added.
According to Van Kerkhove, the WHO Technical Advisory Committee for Virus Evolution will be meeting "regularly" concerning the new variant.
She noted, however, that tests can take days and weeks to receive results that could provide a better understanding of the impacts with omicron.
Until more information is found, Van Kerkhove encouraged people to prevent their exposure to COVID infection by distancing, wearing a mask, avoiding crowded spaces, consistently washing hands and getting vaccinated.
Does Pfizer's pill to treat COVID work against the omicron variant?
Pfizer said this week that its experimental pill to treat COVID-19 appears effective against the omicron variant.
The company also said full results of its 2,250-person study confirmed the pill's promising early results against the virus: The drug reduced combined hospitalizations and deaths by about 89% among high-risk adults when taken shortly after initial COVID-19 symptoms.
Separate laboratory testing shows the drug retains its potency against the omicron variant, the company announced, as many experts had predicted. Pfizer tested the antiviral drug against a man-made version of a key protein that omicron uses to reproduce itself.