Beginning Feb. 15, anyone coming to the United Kingdom from a country on its travel ban list of COVID-19 hotspots must quarantine in a government-approved hotel for 10 nights, the U.K. government announced Thursday.

Most foreign nationals from high-risk nations already face U.K. travel restrictions due to the coronavirus pandemic. But this new rule will apply to U.K. citizens and residents arriving from one of the 33 "red list" countries: Angola, Argentina, Bolivia, Botswana, Brazil, Burundi, Cape Verde, Chile, Colombia, Democratic Republic of the Congo, Ecuador, Eswatini, French Guiana, Guyana, Lesotho, Malawi, Mauritius, Mozambique, Namibia, Panama, Paraguay, Peru, Portugal (including Madeira and the Azores), Rwanda, Seychelles, South Africa, Suriname, Tanzania, United Arab Emirates, Uruguay, Venezuela, Zambia and Zimbabwe.

Security will escort guests to their quarantine rooms when they arrive and must accompany them if they wish to access outside space for fresh air or a smoke. Three meals per day and laundry service will also be provided during their stay.

Those in quarantine will be required to take a COVID-19 test on both Day 2 and Day 8.

ABC News’ Zoe Magee contributed to this report.

Denmark, the Netherlands and Norway have joined the growing list of European countries that have said they won't recommend older age groups receive the COVID-19 vaccine developed by England's University of Oxford and British-Swedish pharmaceutical giant AstraZeneca until more data from clinical trials becomes available.

The Danish Health Authority said Thursday that it will recommend the Oxford/AstraZeneca vaccine to people under the age of 65 who are not at risk of serious illness from COVID-19. The drugs regulator citied a lack of documentation as to the vaccine's efficacy in older age groups.

The Norwegian Institute of Public Health said it will also limit use of the Oxford/AstraZeneca vaccine to those under 65 because there had been few participants older than that in the trial conducted by AstraZeneca.

Meanwhile, the Dutch Health Council said the efficacy of the Oxford/AstraZeneca vaccine in those over 55 "cannot yet be calculated because they participated only to a limited extent in the vaccine studies."

Belgium, France and Germany have made similar moves recently, while Switzerland went a step further and declined to authorize the Oxford/AstraZeneca vaccine for any age group, citing insufficient data.

The number of COVID-19 vaccine doses delivered across the United States over the past week dropped 22.5%, but the amount of doses administered increased 13.5%, according to a report from the U.S. Department of Health and Human Services.

The country has also seen a three-week downward trend in new COVID-19 cases, resulting in a 44% decline in the seven-day daily average since the peak on Jan. 8, the report said.

Still, the current number of daily cases remains over twice as high as the numbers during prior peaks.

ABC News’ Brian Hartman and Josh Margolin contributed to this report.

There are currently 91,000 people hospitalized with COVID-19 in the United States -- the lowest since Nov. 28, which was two days after Thanksgiving, according to an ABC News analysis of data compiled by The COVID Tracking Project, a volunteer-run effort to track the U.S. outbreak.

COVID-19 hospitalizations have declined across the country by nearly 30% over the last three weeks.

In the span of three weeks, the national seven-day average of daily COVID-19 cases has declined by 45.6% -- the steepest and most consistent non-holiday-related drop in cases the U.S. has seen since the summer.

ABC News’ Arielle Mitropoulos contributed to this report.

Cases of the more contagious U.K. variant of the COVID-19 virus is spreading rapidly through the U.S., as much as doubling every 10 days, a new study suggests.

The study has not peer reviewed, so it has not been scrutinized for inaccuracies or context by specialists.

It is still not known whether the U.K. variant is more virulent or deadly, but it is more transmissible. The Centers for Disease Control and Prevention warned last month that the U.K. variant could become predominant in the U.S. by March if spread the way it did in the U.K.

Vaccines don’t seem to be strongly impacted by the U.K. variant, but scientists are concerned about the efficacy of the vaccines against the South African variant.

-ABC News’ Eric Strauss