Matthew S. Schwartz

Updated at 6:43 p.m. ET

One day after a Christmas bombing in downtown Nashville, Tenn., damaged dozens of buildings over several blocks and injured at least three people, police are working with federal authorities to find the perpetrator.

In his Christmas Day address, Pope Francis appealed to the nations of the world to share the new coronavirus vaccines with the most needy.

"Today, in this time of darkness and uncertainty regarding the pandemic, various lights of hope appear, such as the discovery of vaccines," Francis said. "But for these lights to illuminate and bring hope to all, they need to be available to all."

The United Kingdom has entered a period of intense restrictions after a mutation of the coronavirus was discovered spreading rapidly through the population of London and the southeast and east of England. Most of the country faces a strict lockdown as Christmas approaches, and several countries throughout Europe have banned travel from the United Kingdom.

The British government put several parts of England into what's known as "Tier 4" restrictions after the spike in infections. Prime Minister Boris Johnson announced the new restrictions on Saturday.

The Army has soldiers. The Navy has sailors. Now, one year after its creation, it's official: The Space Force has "guardians."

Vice President Mike Pence revealed the moniker during remarks celebrating the first anniversary of the military branch on Friday.

With a hard end-of-year deadline looming, the U.K. and the European Union will continue negotiations to try to avoid a no-deal Brexit, European Commission President Ursula von der Leyen announced on Sunday.

Taking the podium at EU headquarters in Brussels, Von der Leyen said that despite the lack of any breakthrough, talks to determine the two sides' future trading relationship would continue. Von der Leyen said she had a "constructive and useful phone call" with British Prime Minister Boris Johnson, in which they discussed "major unsolved topics."

Democracy activist Jimmy Lai, a prominent Hong Kong media mogul charged with violating a new and controversial national security law, was denied bail Saturday.

Lai, who publishes a tabloid newspaper that's critical of China, is one of the most high-profile people charged with colluding with a foreign country under a controversial new national security law. China's ruling Communist Party has been taking its most prominent critics into custody as it attempts to suppress the pro-democracy movement there.

Updated at 5:07 p.m. ET

President Trump's personal attorney, Rudy Giuliani, has tested positive for the coronavirus, according to the president. Trump made the announcement on Twitter on Sunday afternoon.

As U.S. health authorities continue examining the proposed COVID-19 vaccines, residents in the United Kingdom — the first Western country to issue approval for emergency use — are set to receive their first shots as early as this week.

But quickly vaccinating as many people as possible in the U.K. will pose enormous logistical challenges — from keeping the doses frozen to figuring out how to methodically and fairly distribute the vaccine across the nation of 68 million.

The number of hospitalizations from the coronavirus set yet another record on Saturday, as cases continue to surge and public health officials warn of a worsening outlook with the holiday season just weeks away.

More than 91,500 people were hospitalized with the virus on Saturday, with 18,000 in intensive care units. That's according to data compiled by the COVID Tracking Project, which collects and analyzes data from across the United States. Over 6,000 patients were on ventilators.

Tony Hsieh, who helped grow the online company Zappos into one of the largest retailers of shoes on the Internet, died Friday after being injured in a house fire. He was 46.

"The world has lost a tremendous visionary and an incredible human being," Zappos CEO Kedar Deshpande said in a statement. "We recognize that not only have we lost our inspiring former leader, but many of you have also lost a mentor and a friend."

Updated at 6:54 a.m. ET Saturday

A top Iranian scientist believed to be responsible for developing the country's military nuclear program was killed Friday, causing outrage in Iran and raising U.S. concerns over potential retaliation.

The strongest tropical cyclone ever measured in the northern Indian Ocean has made landfall in eastern Africa, where it is poised to drop two years' worth of rain in the next two days.

Tropical Cyclone Gati made landfall in Somalia on Sunday with sustained winds of around 105 mph. It's the first recorded instance of a hurricane-strength system hitting the country. At one point before landfall, Gati's winds were measured at 115 mph.

One of the experimental drugs that President Trump received while he was battling the coronavirus has been approved for emergency use by the Food and Drug Administration. The drug, made by the biotech company Regeneron, is the second antibody treatment to win emergency use approval from the FDA.

The treatment combines two antibodies — casirivimab and imdevimab — and administers them together by IV. In a clinical trial of about 800 people, the combination was shown to significantly reduce virus levels within days of treatment.

Donald Trump Jr. has become the latest member of the president's orbit to test positive for the coronavirus.

"Apparently I got the 'rona," the president's son told his Instagram followers late Friday.

"You wouldn't know it based on anything that I felt or have seen," he said. "I've been totally asymptomatic."

The Trump administration has not cooperated with President-elect Joe Biden's transition team, and top Biden officials say the incoming president is limited in what he can do before his team takes the reins. Still, Biden's coronavirus advisory board co-chair Vivek Murthy says they're doing everything they can to ensure plans are ready to go on Inauguration Day — including stronger mask requirements.

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