Seven states, all in the South, have intensive care units over 90% full, according to federal data: Alabama (100%), Florida (94.98%), Georgia (94.68%), Louisiana (90.15%), Mississippi (92.07%), Oklahoma (91.68%), and Texas (93.86%).

The U.S. is continuing to experience its steepest and most significant increase in hospitalizations in seven months, according to federal data. On Wednesday alone, more than 12,800 patients were admitted to the hospital with COVID-19, marking the highest number of patients seeking care over the span of 24 hours since January.

-ABC News' Arielle Mitropoulos

Half of all U.S. 12- to 17-year-olds have had their first vaccine shot, White House COVID-19 coordinator Jeff Zients said at Friday's briefing, which he called "critical progress."

"The vaccination rate among adolescents is growing faster than any other age group," Zients added.

CDC Director Rochelle Walensky said a new CDC report out of Los Angeles County showed that schools following the health agency's guidelines had 3.5 times lower cases during the winter peak as compared to case rates in the community. (This study did not account for the delta variant).

"Even when communities were experiencing high levels of COVID transmission, in the LA County study, layered prevention measures in schools provided a shield of protection, helped to keep COVID out of school and reduced the spread when cases did occur," Walensky said.

She continued: "I want to strongly appeal to those districts who have not implemented prevention strategies and encourage them to do the right thing to protect the children under their care."

-ABC News' Cheyenne Haslett

A Tallahassee judge ruled Friday that Florida school boards can enact student mask mandates, going against Gov. Ron DeSantis, who in July issued an executive order that set off a public feud with school districts.

Judge John C. Cooper found that a blanket ban on face masks in schools "does not meet constitutional muster" and ordered the Florida Department of Education to stop enforcing a state rule that requires districts to allow parents to opt-out of mask mandates.

Cooper, over about two hours, picked apart the state's defense, saying the science presented during the weeklong trial did not support the state's argument against masking children.

Ten Florida school districts have adopted mask mandates for students this month. Two -- Broward and Alachua -- were sanctioned by the Florida commissioner of education, who said he would begin withholding the salaries of board members who voted to require masks.

DeSantis will "immediately appeal" the ruling, the governor's press secretary, Christina Pushaw, said in a statement. "This ruling was made with incoherent justifications, not based in science and facts," Pushaw said.

A spokesman for the Florida Department of Education said, "We are immensely disappointed that the ruling issued today by the Second Judicial Circuit discards the rule of law. This decision conflicts with basic and established rights of parents to make private health care and education decisions for children. ... We are committed to the fundamental rights of parents and will push forward on appeal to ensure that this foundation of democracy is upheld."

-ABC News' Will McDuffie

As Kentucky Gov. Andy Beshear announced the state's third-highest day of COVID-19 cases, he said at a news conference Thursday, "I’m gonna admit up front today I’m a little emotional and a little raw."

"Seeing nearly 5,000 cases and 65 Kentuckians that we lost in just one day’s report is tough," the governor said, adding that "it is entirely preventable."

Hospitalizations have increased every day in the last 42 days, he said.

On July 14, there were 60 people in intensive care units. As of Wednesday there were 549, he said.

At the beginning of the summer Kentucky's positivity rate fell to 1.79%. It's now soared to 13.16%, he said.

Japan has suspended the use of about 1.63 million doses of Moderna's COVID-19 vaccine due to reported contamination, as the country grapples with surging infections.

Japanese drugmaker Takeda Pharmaceutical Co., which is in charge of distributing the Moderna vaccine in Japan, said in a press release Thursday that it has received reports of foreign substances in some unused vials at multiple inoculation sites. Although some doses might have been administered, Takeda said there have been no reports of safety concerns tied to the affected vials so far.

After consulting with Japan's Ministry of Health, Labor and Wealth, Takeda said it decided as a safety precaution to stop using doses from three separate lots, manufactured in the same production line as the contaminated vials. The company said it has requested Moderna to conduct an emergency investigation into the issue.

For doses from non-suspended lots, Takeda urged people to check the vials for discolouration, foreign substances or other abnormalities before continuing to use. Meanwhile, the Japanese health ministry said it will work with Takeda to supply alternative doses in an effort to minimize the impact on the country's vaccination progress.

Moderna told ABC News that it has put the 1.63 million doses on hold in Japan after being notified that some of the vials may have been contaminated. One of the three lots received "several complaints of particulate matter" in its vials, the American drugmaker said, while the two other adjacent lots were put on hold out of "an abundance of caution" and for continued assurance of quality.

According to Moderna, the manufacturing issue may have come from one of the lines used at its contract manufacturing site in Spain. The Massachusetts-based company said it is looking into the contamination reports and "proactively communicating with Japan’s health authorities and its partners as the investigation proceeds." Moderna added that it remains "committed to working transparently and expeditiously" with its Japanese distribution partner and with regulators to address any potential concerns. No safety or efficacy concerns have been identified so far, the company said.

Moderna noted that the pause in Japan does not impact doses distributed in the United States, or put the American supply at risk in any way.