Department of Homeland Security Secretary Alejandro Mayorkas has tested positive for COVID-19, a DHS spokeswoman confirmed to ABC News.

Mayorkas, who is fully vaccinated, "is experiencing only mild congestion," a statement said.

Mayorkas will work from home, the statement said. Contact tracing is underway.

There were no major White House officials deemed to be close contacts. "No White House principal has been determined to be a close contact of Secretary Mayorkas, given that the most recent contact was at the outdoor National Peace Officers’ Memorial Service, which took place outside of the 48-hour close contact window,” the White House said in a statement.

-ABC News' Luke Barr

A new CDC study found that the Pfizer vaccine was 93% effective against hospitalizations for adolescents ages 12 to 18 from July to September.

The researchers also found that nearly all (97%) of adolescents ages 12 to 18 who were hospitalized with COVID-19 were unvaccinated.

-ABC News' Sony Salzman

Ten states -- all of which have colder temperatures -- have seen upticks in hospital admissions in recent weeks, according to federal data: Alaska, Colorado, Maine, Michigan, Minnesota, New Hampshire, North Dakota, Pennsylvania, Vermont and Wyoming.

However, nationwide, just under 58,000 Americans remain hospitalized, a major drop from 104,000 patients at the end of the summer, according to federal data.

Death rates remain high, with more than 1,000 Americans dying each day, according to federal data.

Over the last month, the U.S. has reported approximately 45,000 COVID-19 deaths, including nearly 7,600 deaths in the last week.

-ABC News' Arielle Mitropoulos

The United Kingdom recorded 233 COVID-19 deaths in the last 24 hours, the highest total since March 5, according to government data.

In a statement confirmed by ABC News, issued before the new figures were published, the prime minister’s office said it was keeping a "very close eye" on the numbers and urged people to get their booster shots.

"We have seen case rates rising, we've started to see some indications that hospitalisations and death rates are increasing also," a spokesman for the prime minister said. "It's important that the public understand that getting your booster jab is just as important as getting your first and second dose."

-ABC News' Guy Davies

Coronavirus infections are steadily falling across the country, thanks to significant declines in highly populated states such as Florida, Texas, Louisiana and Mississippi.

The number of daily cases in the U.S. has dropped 50% since Sept. 1, with a 43% drop in hospitalizations and a 21% drop in daily deaths.

However, an uptick in cases in Northern states is causing some concern.

In recent weeks, coronavirus infections have been creeping up in several states in the Upper Midwest and the Northeast. Eight states — Alaska, Colorado, Idaho, Michigan, Minnesota, New Hampshire, New Mexico, and Vermont — have seen notable jumps in their case averages.

Experts have been warning for weeks that Northern states could begin to see upticks in the coming weeks as winter approaches, and people start to head indoors.

Alaska currently has the country's highest case rate, followed by Montana, Wyoming, Idaho, West Virginia, and North Dakota, which all with case rates above 400 per 100,000 people.

Daily deaths are slowly falling, but remain persistently high. The nation is still reporting an average of 1,250 new deaths each day, and over the last four days alone, the U.S. reported just under 7,000 confirmed COVID-19 deaths.

The death average is still about 6.5 times higher than in mid-July, when the national average had dropped to a near pandemic low of 192 deaths reported each day.

Nationally, hospitalization numbers have dropped to under 60,000 patients with COVID-19 currently receiving care, down from 104,000 patients in late August. Hospital admissions have also fallen by about 10.4% in the last week.

Approximately 113.5 million Americans remain completely unvaccinated. Just under 65.2 million of those people are over the age of 12. The other 48 million unvaccinated people are children under the age of 12.

— ABC News’ Arielle Mitropolous