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

Hours after the unanimous vote from its independent advisory committee, the Centers for Disease Control and Prevention has signed off on recommending booster shots for the Moderna and Johnson & Johnson COVID-19 vaccines for certain populations.

CDC Director Rochelle Walensky recommended boosters for Pfizer and Moderna recipients with no preference on the brand, leaving that decision up to the individual.

People who are 65 and older, or individuals as young as 18 who have underlying medical conditions or live in high-risk or long-term care settings, are eligible to receive either a Pfizer or Moderna booster at least six months after their second shot, the CDC said.

The one-shot Johnson & Johnson vaccine is eligible to anyone aged 18 and up, at least two months after their initial dose, the CDC said.

-ABC News' Eric Strauss