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

Beginning Wednesday, states can start reserving vaccines for kids ages 5 to 11, though vaccines won't start shipping yet.

The government has purchased enough shots for all 28 million children ages 5 to 11 in the U.S.

On Oct. 26, the FDA advisory committee is expected to have a public discussion and have a non-binding vote on the matter. Within days of that vote, the FDA is expected to authorize the vaccine for kids ages 5 to 11.

On Nov. 2 and Nov. 3, a CDC committee is expected to have a public discussion and non-binding vote.

The CDC director is likely to issue a formal recommendation within hours of the expected Nov. 3 vote. Administration of vaccine for 5- to 11-year-olds may begin as soon as the CDC director signs off.

-ABC News' Eric M. Strauss