Last week, another 164,000 children in the United States tested positive for COVID-19, up by 24% from the week prior, according to a report released Monday by the American Academy of Pediatrics and the Children’s Hospital Association.

COVID-19 cases among U.S. children are "extremely high," the organizations wrote in the report.

Last week the Northeast saw its highest number of pediatric cases since the onset of the pandemic, with nearly 40,000 new cases.

So far, 21 million children ages 5 to 17 nationwide -- about 39.6% -- have received at least one dose of a COVID-19 vaccine.

Severe illness due to COVID-19 remains "uncommon" among children, the organizations wrote in the report. But they continue to warn that there is an urgent need to collect more data on the long-term consequences of the pandemic on kids, including the physical, emotional and mental health impacts.

-ABC News' Arielle Mitropoulos

A total of 50 million COVID-19 cases have now been confirmed in the U.S., according to data from Johns Hopkins University.

The U.S. has reported more cases than any other nation in the world. The U.S. currently represents nearly one-fifth of the globe's total 270.5 million cases.

-ABC News' Arielle Mitropoulos

In the weeks following Thanksgiving, the COVID-19 resurgence in the U.S. has escalated rapidly.

The U.S. is averaging more than 118,000 new cases each day -- up by about 41.8% in the last two weeks and up nearly 85% since late October, according to federal data.

Six states with some of the nation's highest vaccination rates are also among the states with the highest new case rates: New Hampshire, Vermont, Massachusetts, Maine, Rhode Island and New York. Experts say cases could be rising in the Northeast partially due to people heading inside in the cold weather.

Daily COVID-19-related hospital admissions increased by 14.4% in the last week and jumped by 48% in the last month, according to federal data.

Pediatric admissions are up by 23.8% in the last week.

-ABC News' Arielle Mitropoulos

Omicron is expected to be the dominant variant in London in the next 48 hours, the Secretary of State for Health and Social Care, Sajid Javid, warned in a statement to Parliament Monday.

Omicron represents 20% of England's cases and 44% of London's cases, Javid said.

"No variant of COVID-19 has spread this fast," Javid said.

Ten people with omicron are in U.K. hospitals.

"Hospitalisations and deaths lag infections by around two weeks," Javid said, "So we can expect those numbers to dramatically increase in the days and weeks that lie ahead."

"In preparation, the UK’s four Chief Medical Officers raised the COVID Alert level to 4, its second-highest level, this was done over the weekend. And NHS England has just announced it will return to its highest level of emergency preparedness: Level 4 National Incident," Javid said. "This means the NHS response to Omicron will be a coordinated as a national effort, rather than led by individual trusts."

Javid also urged people to get booster doses, stating that 40% of adults in the U.K. have gotten boosters so far.

-ABC News' Zoe Magee

A journalist traveling alongside U.S. Secretary of State Antony Blinken on his visit to Southeast Asia has tested positive for COVID-19 in Malaysia, according to U.S. Department of State spokesperson Ned Price.

Meanwhile, Blinken and his senior staff all tested negative for COVID-19 upon arrival in Kuala Lumpur on Tuesday night. The member of the traveling press pool who tested positive had last tested negative in Indonesia's capital, their previous stop, on Tuesday.

"The individual who tested positive will remain in isolation," Price said in a statement Wednesday, "and we will continue to adhere to and go beyond CDC guidance, including with our rigorous testing protocol, for the remaining traveling party."

Blinken has canceled a scheduled trip to Thailand "out of an abundance of caution" and will return home to the United States, according to Price.

"The Secretary expressed his deep regret to the Foreign Minister that he would not be able to visit Bangkok this week," Price said. "He explained that, in order to mitigate the risk of the spread of COVID-19 and to prioritize the health and safety of the U.S. traveling party and those they would otherwise come into contact with, the Secretary would be returning to Washington, D.C. out of an abundance of caution."

"The Secretary extended an invitation for the Foreign Minister to visit Washington, D.C. at the earliest opportunity and noted that he looked forward to traveling to Thailand as soon as possible," Price added. "They affirmed that they would use the upcoming engagements to further deepen the U.S.-Thai alliance."

The U.S. Embassy in Malaysia confirmed that the infected individual "was not involved and has not participated in any of Secretary Blinken's program in Kuala Lumpur."

"The sole member of the traveling party who tested positive is observing all requirements of the Ministry of Health," the embassy said in a statement Wednesday. "We confirm all other members of the party tested negative for COVID-19 upon arrival in Malaysia."

Blinken was in Indonesia on Tuesday, and the U.S. Embassy in Jakarta confirmed that no members of the traveling party tested positive for COVID-19.

All members of the U.S. delegation are required to be vaccinated against COVID-19 and undergo regular testing on trips.

-ABC News' Conor Finnegan