Months after Delta threatened the fall back-to-school ritual, COVID-19 is again complicating kids' return to the classroom.

Why it matters: While government officials worked to convince school administrators and parents over the last several days that kids could safely get back to in-person learning after the holidays, the reality on the ground amid the spread of Omicron is much more complicated.

What they're saying: "I still believe very firmly and very passionately, not only as an educator but as a parent, that our students belong in the classroom and that we can do it safely," Education Secretary Miguel Cardona said on CBS' "Face the Nation" on Sunday.

Yes, but: While many of the nation's school districts are moving ahead with in-person classes, more than 2,100 schools are expected to be closed or open only for remote instruction this week, according to the school tracking website Burbio.

Among the concerns, Omicron numbers are surging and hospitals are already filling up or overwhelmed, fueling concerns that kids' return to schools could further drive up case rates.

• Pediatric hospitalizations have hit record levels, largely attributed to large numbers of kids being not fully vaccinated against COVID.
• While the Biden administration announced a "test-to-stay" strategy last month to keep schools open, the logistics so far have proved challenging as tests in many places were delayed, the Wall Street Journal and USA Today reported.

The bottom line: As the U.S. gets back to business and school in the new year, Americans will be adjusting to increased testing, changing isolation protocols, and evolving views on the importance of mask quality.

• Amid the spread of a highly transmissible variant, the next few weeks could prove to be especially challenging.

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🎙 Listen in: The Axios Today podcast covers back-to-school and COVID testing.

Federal law now bans many types of out-of-network medical bills and puts the onus on doctors and health insurance companies to resolve their payment disputes, Axios' Bob Herman reported over the weekend.

Why it matters: Consumers can breathe a sigh of relief because, in many scenarios, they should no longer face unexpected charges from doctors who are not in their insurance networks.

How it works: Patients still have to pay in-network copays, deductibles and other cost-sharing, which have been rising, but any additional out-of-network bills are now prohibited for the following services:

• Emergency care in a hospital ER, a freestanding ER or urgent care center.
• Elective care at an in-network hospital or surgery center, but where doctors — notably anesthesiologists, pathologists, radiologists and assistant surgeons — may be out-of-network. This is also known as "drive-by doctoring."
• Air ambulances.

Of note: Ground ambulances are not included in this law, meaning three out of four insured people who take an ambulance ride are still at risk of facing surprise bills.

Behind the scenes: Instead of sending out bills, doctors and insurance companies have to resolve their differences while holding the patient harmless.

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Botox sales have never been higher.

By the numbers: U.S. sales of Botox — just the cosmetic version that is used to smooth out face wrinkles, and not the version that is used to treat conditions like migraines and neck spasms — surpassed $1 billion in the first nine months of 2021, compared with $600 million in the first nine months of 2020, Bob writes.

• The revenue jump stems from "brand investment and strong recovery from the COVID-19 pandemic," according to financial filings from AbbVie, which bought the company that makes Botox in 2020.
• China is the second-biggest Botox market after the U.S., driving total international sales to $579 million in the first nine months of this year.

What they're saying: "At this point, we're not seeing [growth] driven by pent-up demand as much as just fundamental demand," Carrie Strom, a senior vice president at AbbVie who oversees the company's cosmetic drugs, said at an investment bank conference this month.

The largest manufacturers of rapid, at-home COVID-19 tests created a new lobbying group urging Medicare to pay for their tests, according to federal lobbying disclosures, Bob reports.

Why it matters: Rapid tests are increasingly important as the Omicron variant takes hold, but the costs and supply of tests have been a sticking point.

The big picture: For PCR COVID tests, which require people to go to a hospital, pharmacy or testing site, Medicare and private insurers cover them at no cost under federal law.

Yes, but: Medicare was not part of the White House's rapid test rollout.

• What to watch: Federal guidance on rapid test reimbursement is supposed to come out no later than Jan. 15, and based on recent comments from Health and Human Services Secretary Xavier Becerra and the formation of this lobbying group, it's possible Medicare coverage could be part of it.

• ICYMI: What to expect from America's third year of COVID. (Axios)
• CES to end a day early amid Omicron and cancellations. (Axios)
• New York jury finds drugmaker Teva liable in opioid epidemic. (Axios)
• The Biden administration rejected an October proposal for "free rapid tests for the holidays." (Vanity Fair)
• First patients in Israel receive Pfizer's coronavirus-fighting pill. (Times of Israel)