Chicago's first Omicron case in boosted resident

The first Chicago case of the Omicron variant was detected Tuesday in a resident who was both vaccinated and boosted.

Why it matters: The new variant could boost already surging cases in Chicago.

Threat level: The city is taking several precautionary measures, health commissioner Allison Arwady said Tuesday at her weekly press conference, including:

• Contacting all U.S. citizens arriving at O'Hare from eight restricted countries.
• Testing known contacts of individuals infected with Omicron.
• Doubling COVID samples sequencing at public labs.
• Requiring all international travelers to get COVID tests within a day of their trip.

The latest: Thanksgiving guests with the the sniffles drove the post-holiday Delta surge.

• "We found people went to Thanksgiving even though they had some symptoms they thought were a cold ... and some cases of folks who had gone to get tested and hadn't yet gotten the [positive] results back," the health commissioner said.
• "Stay home if you feel sick."

What's next: Arwady answered questions on the need for:

• Omicron boosters: "We might. We'll know in another two weeks or so once all the data has been collected."
• Continued indoor masking: "Yes, especially as cases are on the increase. We will be doing messaging on [best] types of masks soon."
• More stringent proof of vaccination: "Yes, I think we might. I'm more interested in that than major shutdowns."