COVID-19 updates: Classes in Chicago canceled for 4th day

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.

The seven-day positivity rate at the U.S. Capitol COVID-19 testing center has increased from 1% to 13%, according to a letter sent from the Office of the Attending Physician to congressional offices on Monday.

Most cases have been breakthroughs among people who are fully vaccinated and have not “led to hospitalizations, serious complications, or deaths, attesting to the value of coronavirus vaccinations," the letter reads.

The letter also states that about 61% of COVID-19 infections at the Capitol have been linked to the omicron variant, and 38% are linked to the delta variant.

The OAP advised congressional offices to telework as much as possible and that "blue surgical masks, cloth face masks and gaiter masks must be replaced by the more protective KN95 or N95 masks."

New York City Mayor Eric Adams insisted that schools will stay open for in-person leaning despite the rapidly rising number of COVID cases.

“We’re really excited about the opening of our schools,” he said during a speech outside Concourse Village Elementary School in the Bronx on Monday. “We want to be extremely clear: the safest place for our children is a school building.”

As part of a plan to curb rates of infection, 1.5 million rapid at-home test kits are being being distributed to schools.

Students and adults who exhibit symptoms or have been exposed to a positive case will be required to have two negative tests over the course of five days before they can return to classes.

On Sunday, Adams told ABC's "This Week" that parents should "fear not sending [kids] back" to school after the winter break.

Meanwhile, several other school districts across the country, including Atlanta, Cleveland, Newark and Milwaukee, have opted for virtual learning for at least the first week of the new semester.