COVID updates: Secretary of Defense Lloyd Austin tests positive

Amidst the nation's latest COVID-19 surge, nearly 200,000 more children tested positive for COVID-19, last week, up by about 50% since the beginning of December, according to a new report from the American Academy of Pediatrics (AAP) and the Children’s Hospital Association (CHA), released on Monday.

This week marks the twentieth consecutive week that pediatric COVID-19 case total has been above 100,000.

COVID-19 cases among children are "extremely high," and increasing, the organizations wrote. 

Children accounted for about 20% of reported weekly COVID-19 cases, last week. For context, children, under age 18, make up 22.2% of the U.S. population.

COVID-19 related hospitalizations among children are also on the rise. On average, about 260 children in the U.S. are being admitted to the hospital with COVID-19 each day, according to federal data, and nearly 2,000 children are currently hospitalized with the virus.

To date, 22.4 million children ages 5 to 17 years-old -- about 42% of that population -- have received at least one dose of a COVID-19 vaccine.

-ABC News’ Arielle Mitropoulos

Delta Airlines announced it is working fast to implement the U.S. Centers for Disease Control and Prevention's latest guidance to reduce the isolation period for some infected patients.

Delta was one of many airlines to call on the federal government to reduce the isolation period from 10 days to five, citing staffing shortages that led to flight cancelations.

"The updated guidance allows more flexibility for Delta to schedule crews and employees to support a busy holiday travel season and a sustained return to travel by customers," the airline said in a statement.

Delta did not give more details as to when their new policy will take effect.

-ABC News' Mina Kaji

The U.S. Centers for Disease Control and Prevention announced Monday afternoon it will shorten the recommended isolation time for some people infected with COVID-19.

Patients who are asymptomatic will have to isolate for five days, followed by five days of wearing a mask around others, under the new guidance. Previously, the isolation period was 10 days for everyone.

Individuals who have received their booster shot do not need to quarantine following an exposure, but should wear a mask for 10 days after the exposure, the CDC said.

"The Omicron variant is spreading quickly and has the potential to impact all facets of our society. CDC’s updated recommendations for isolation and quarantine balance what we know about the spread of the virus and the protection provided by vaccination and booster doses," CDC Director Dr. Rochelle Walensky said in a statement.

The Texas Department of State Health Services announced Monday that centers in Austin, El Paso, Fort Worth, San Antonio and The Woodlands ran out of sotrovimab, the monoclonal antibody effective against the COVID-19 omicron variant.

The federal government won't be able to ship more supplies of the treatment until January, the department said.

Those centers will still be able to provide monoclonal treatment for any patient who hasn't contracted the omicron variant, according to the department.