A record 325,000 children tested positive for COVID-19 last week amid the nation's most significant COVID-19 infection surge yet, according to the American Academy of Pediatrics and the Children’s Hospital Association.

Children accounted for about 17.4% of last week's reported COVID-19 cases, down from previous weeks, when children accounted for more than a quarter of all new cases.

A total of nearly 7.9 million children have tested positive for the virus, since the onset of the pandemic.

ABC News' Arielle Mitropoulos

New York's hospitals will be required to report a breakdown of how many COVID-19 patients were admitted due to the coronavirus and how many were admitted for other needs and only discovered they were infected during their stays.

During a COVID-19 briefing on Monday, Gov. Kathy Hochul cited anecdotal reports of as many as 50% of patients at some hospitals testing positive for the virus who were actually admitted for other reasons, such as car accidents.

"I just want to always be honest with New Yorkers about how bad this is," Hochul said. "Yes, the sheer number of people infected are high, but I want to see whether or not the hospitalizations correlate with that."

She continued, "And I'm anticipating to see that at least a certain percentage overall are not being treated for COVID."

Hospitals will begin reporting their breakdowns Tuesday, but it's unclear how soon the data will be publicly available.

-ABC News' Joshua Hoyos and Will McDuffie

U.S. Surgeon General Dr. Vivek Murthy warned that COVID-19 cases and hospitalizations will continue to increase as the omicron variant rapidly spreads across the country.

"The next few weeks are going to be tough for us," he told ABC's "The View" on Monday. "We’re already seeing record levels of cases, and we're seeing hospitalizations starting to tick up. We're seeing some of our hospital systems getting strained at this point."

Information from South Africa and the United Kingdom indicates omicron could be less severe than previous COVID-19 variants, Murthy said.

"We’re still going to see a lot of people get sick and a lot of hospitalizations, but the overall severity may end up being significantly lower," he said.

Murthy said both South Africa and the U.K. "had a very rapid rise, but then they had a very steep fall" in cases

"I'm hoping that that’s what happens here too," he added.

-ABC News' Joanne Rosa

Starbucks is requiring its 220,000 workers to get the COVID-19 vaccine or be tested weekly, complying with the Biden administration's vaccine mandate for private businesses.

Employees must reveal their vaccination status by Jan. 10, according to a letter sent Monday by Starbucks Chief Operating Officer John Culver, Reuters first reported.

"This is an important step we can take to help more partners get vaccinated, limit the spread of COVID-19, and create choices that partners can own based on what's best for them," Culver wrote.

Workers will have until Feb. 9 to be fully vaccinated.

Those who choose to undergo weekly testing instead will be responsible for obtaining their own tests -- which cannot be self-administered or taken at home -- and submitting results.

Dr. Rochelle Walensky, director of the U.S. Centers for Disease Control and Prevention, is standing by her agency's new quarantine and isolation guidance for COVID-19, which the nation’s largest association of physicians has criticized as "confusing."

The CDC updated its guidelines on Dec. 27, saying asymptomatic people who test positive for COVID-19 should self-isolate for five days rather than 10. In a scathing statement released Wednesday night, the American Medical Association (AMA) said the new recommendations "are risking further spread of the virus."

"The American people should be able to count on the Centers for Disease Control and Prevention (CDC) for timely, accurate, clear guidance to protect themselves, their loved ones, and their communities. Instead, the new recommendations on quarantine and isolation are not only confusing, but are risking further spread of the virus," the AMA's president, Dr. Gerald E. Harmon, said in the statement. "With hundreds of thousands of new cases daily and more than a million positive reported cases on January 3, tens of thousands -- potentially hundreds of thousands of people -- could return to work and school infectious if they follow the CDC’s new guidance on ending isolation after five days without a negative test."

But Walensky defended the new guidance, telling ABC News' Cecelia Vega in an interview Friday on "Good Morning America" that the CDC "make[s] these recommendations in the context of science, in the context of ongoing epidemiology and in the context of what is feasible in collaboration with our public health and local and state public health partners."

"I've read the AMA statement and I have deep respect for the AMA," Walenskey said, "but I will also say we've heard a lot of support for ongoing guidance from public health partners, from other clinical and laboratory partners as well."

Walensky referenced "dozens of studies" that have shown a COVID-19 patient is most infectious in the one to two days before symptoms and the two to three days after symptoms.

"So by five days after your symptoms, the vast majority of your contagiousness is really behind you," she said. "And what we say at day five then is, are your symptoms gone? Are you feeling better? Is your cough gone, sore throat gone? And if so, then it is safe to go out if you are wearing a mask all the time. And that means not going out to restaurants, not going out to gyms, not going out and visiting grandma, but really conscientiously wearing your mask for those last five days."

Walensky noted that people may choose to take an antigen or at-home test at day five, if they have access to one. But it's not required.

"If that test is positive, you should stay home for those extra five days. But if that test is negative you should go out and continue to wear your mask," she said. "You know, these tests are actually not authorized for the purpose of evaluating contagiousness."