Since omicron was first identified 10 weeks ago, nearly 90 million COVID-19 cases have been reported around the world -- more than all the COVID-19 cases reported in 2020, according to the World Health Organization.

Now most regions of the world are "starting to see a very worrying increase in deaths," WHO director-general Dr. Tedros Adhanom Ghebreyesus warned Tuesday.

"This virus will continue to evolve, which is why we call on countries to continue testing, surveillance and sequencing. We can’t fight this virus if we don’t know what it’s doing. And we must continue to work to ensure all people have access to vaccines," he said.

-ABC News' Christine Theodorou

Pfizer and BioNTech are expected to ask the FDA to authorize their vaccine for kids under 5 as soon as Tuesday. If the FDA grants authorization, the vaccine may be available for children ages 6 months to 5 years by the end of February, The Washington Post reported. 

Pfizer is expected to ask for authorization with two doses as the company continues to wait for data on three doses, the report said.

Vaccines are currently authorized for people 5 and older.

-ABC News' Eric M. Strauss and Cheyenne Haslett

American bobsledder Elana Meyers Taylor has tested positive for COVID-19 upon arriving in Beijing for the 2022 Winter Olympics.

Taylor, 37, announced her positive test in a statement posted on social media Tuesday. The three-time Olympic medalist and mother to a 1-year-old son revealed that she tested positive on Saturday, just two days after arriving in the Chinese capital.

"I am asymptomatic and currently at an isolation hotel -- and yes I am completely isolated," Taylor said. "Getting to the Olympics is never easy, and this time, as a new mom, it has been the most challenging, but also, incredibly rewarding, to be able to show that it can still be done."

"So many people, especially other moms from all walks of life, have been so supportive of my efforts to get back to the Olympics," she continued. "It’s been an incredible wave of positivity that I’ve been riding to a while so I’m going to continue to do that. This is just the latest obstacle that my family and I have faced on this journey, so I'm remaining optimistic that I'll be able to recover quickly and still have the opportunity to compete."

The Winter Games kick off Friday with the opening ceremony. Bobsled competition doesn't start until Feb. 13.

New COVID-19 cases among children dropped last week for the first time since Thanksgiving, according to a new report by the American Academy of Pediatrics and the Children’s Hospital Association. About 808,000 children tested positive last week, down from a peak of 1,150,000 cases reported the week ending Jan. 20.

However, the organizations warn that pediatric cases remain "extremely high," still triple the peak level of the delta surge in the summer of 2021.

AAP and CHA noted there is an "urgent" need to collect more age-specific data to assess the severity of illness related to new variants as well as potential longer-term effects. The two organizations note in their report that a small percentage of pediatric cases have resulted in hospitalization and death.

More than 28 million eligible children remain completely unvaccinated, according to federal and census data.

-ABC News' Arielle Mitropoulos