Hope you're flu-free! Welcome to the Daily Briefing. Here’s what’s breaking this morning:

• Messy weather threatens post-holiday travel across U.S.

• This crisis affects more than one million American students.

• This Taylor Swift fitness class is going national.

Nicole Fallert here, bringing you the news to know on Monday, from an intense cold and flu season to U.S.-Ukraine peace talks and a look at how Black online gamers found community.

Cough, sniffle, ache

Don't forget your vitamin C: Flu is surging across the country amid a busy holiday travel time.

The state of New York is among those most heavily hit. For the week ending Dec. 20, the state reported its highest number of positive flu cases ever recorded in a single week, according to the New York State Department of Health. That represented an increase of 38% over the previous week, the department said.

The increase in seasonal flu activity across the United States is similar to several past seasons, the CDC says. But it comes along with a new flu strain. Health officials have been concerned the current flu vaccine may be a mismatch to the new variant, but they are confident it has protection against serious illness.

Also potentially contributing to an increase in flu: a decline in Americans getting flu shots.

More news to know now

• Trump says "thorny' issues remain after peace talks with Zelenskyy. A trip to President Donald Trump's Florida resort by Ukrainian leader Volodymyr Zelenskyy failed to cement a peace plan for his war-torn nation. Among the toughest issues is the question of territorial concessions.

• Investors know about the AI bubble. They're buying AI stock anyway. Despite the bubble talk, AI stocks have continued their ascent even though many believe the stocks are historically overpriced. Nvidia was up about 36% through Dec. 23. Alphabet was up about 66%.

• Can border control use Face ID to unlock my phone? Technically, yes, since biometrics are less secure. "Agents can hold your phone up to your face to unlock it without your consent," according to the ACLU's website.

Take a look

Flowing through the slalom

American skier Mikaela Shiffrin extended her win streak in epic fashion. Shiffrin, 30, erased a 0.54-second deficit, her largest in more than a decade, to win the slalom in Semmering, Austria, on Sunday. She is now five-for-five in slalom races this season, and has won six in a row going back to last season.

Something to talk about

They turned a fantasy card game into real community

Magic: The Gathering offers players an escape from reality, where they cast spells and summon creatures rather than worrying about their 9-to-5s. But entering the fantasy world often comes at a cost: Decks can run players hundreds or even thousands of dollars, depending on card rarity. But proxies, or unofficial stand-in cards to represent cards not in a player's collection, and the 2019 launch of MTG Arena, a free-to-play online version of the game, have opened the door to these Black players.

Before you go

• Who is in the NFL playoffs?

• This city rings in the new year with shrimp.

• "Heated Rivarly" got this right about queer travel.

Have feedback on the Daily Briefing? Shoot Nicole an email at NFallert@usatoday.com.

This article originally appeared on USA TODAY: Flu, winter weather, travel, New Years, Ukraine, AI bubble, immigration, NFL playoffs: Daily Briefing