New COVID-19 deaths have increased nearly 14% week-over-week, according to an internal U.S. Health and Human Services memo obtained by ABC News.

There were 18,358 deaths recorded from Dec. 12 to 18 -- marking a 13.8% increase compared with the previous week, the memo said.

During that time, there were over 1.5 million new cases, up 5.6% from the previous seven-day period.

Across the country, 32% of hospitals have more than 80% of their intensive care unit beds filled, 23% of inpatients have COVID-19, and 34% of ventilators in use are occupied by patients with COVID-19.

Hospitalization rates are surging in Arizona, New Hampshire, Nevada, West Virginia, and Washington, D.C., the memo noted.

Fatalities rose 171% in Colorado between the weeks ending Dec. 8 and Dec. 15, it said.

-ABC News' Josh Margolin

The first Moderna vaccines will likely be administered on Monday, U.S. Health and Human Services Secretary Alex Azar said.

Nearly 6 million doses are in the process of [being distributed] (), following emergency use authorization of the vaccine by the Food & Drug Administration.

They will begin delivery on Monday, at which point "we will likely see the first vaccinations with this vaccine," Azar said on Twitter Saturday.

UK Prime Minister Boris Johnson announced a stricter "tier 4" lockdown for London and southeast England on Saturday, citing a rapidly spreading new strain of COVID-19 detected by government scientists.

The new strain was not more dangerous, he stressed during a press briefing, but it was spreading faster, particularly in London and southeast England. The new variant may be 70% more transmissible than any strain previously detected, he said. There is no evidence a vaccine is less effective against it, he added.

The new restrictions go into effect Sunday morning. People are encouraged to stay home, and only one household indoors and two households outdoors will be allowed.

Previously, up to three households could gather from Dec. 23-27.

“We cannot continue with Christmas as planned," Johnson said Saturday.

All nonessential shops, sports facilities and gyms will also close.

The restrictions will last at least two weeks.

-ABC News' Mike Trew contributed to this report

FedEx Express, a subsidiary of FedEx Corp said Saturday it "operations were in motion" to transport the Moderna COVID-19 vaccines for McKesson Corp. throughout the United States.

Federal advisers voted overwhelmingly Thursday to recommend the [Moderna vaccine](} for people over the age of 18, clearing a path for government authorization on what would become the nation's second vaccine to prevent COVID-19.

On Dec. 11, a COVID-19 vaccine developed by Pfizer and BioNTech became the (first COVID-19 vaccine)[] authorized by the Food and Drug Administration for people age 16 and over. Rollout of the first vaccine began Monday, FedEx also began delivering the Pfizer and BioNTech last week.

FedEx Express will begin transport of the vaccine and kits of supplies for administration of the vaccine, using its FedEx Priority Overnight service supported by FedEx Priority Alert advanced monitoring, the company said in its statement.

-Ahmad Hemingway, Anne Flaherty, Stephanie Ebbs, Sophie Tatum, Arielle Mitropoulos and Ivan Pereira