Injections of the newly authorized Moderna vaccine are now underway in the U.S.

In Boston, health care workers at the East Boston Neighborhood Health Center were among the first people to receive Moderna's vaccine. Dr. Jaime Gallegos, the first staffer to get the vaccine, held a sign that said, "Take that, COVID!"

The first cases containing the Moderna vaccine -- which was authorized by the FDA on Friday -- were seen Sunday morning being rolled out from a facility in Olive Branch, Mississippi, to be shipped to the FedEx hub in Memphis, Tennessee, for nationwide distribution.

The doses were packed into insulated coolers with specialized cold packs and a temperature monitor, according to pharmaceutical distribution company McKesson.

ABC News’ Arielle Mitropoulos contributed to this report.

The European Commission authorized the Pfizer vaccine on Monday, hours after the European Medicines Agency issued a recommendation granting a conditional marketing authorization (formal authorization) for the vaccine.

"It will be available to all EU countries at the same time, on the same conditions," tweeted EU Commission President Ursula von der Leyen.

French Prime Minister Jean Castex tweeted, "Vaccination will start in the 27 EU countries on December 27, 28 and 29."

ABC News’ Ibtissem Guenfoud contributed to this report.

The reproduction rate of a new COVID-19 variant linked to an uptick in cases in England is 0.4 higher than other known strains, Dr. Maria Van Kerkhove, the World Health Organization’s COVID-19 technical lead, said Monday.

That means the number of people an infected individual transmits to increases from 1.1 to 1.5 with the new variant.

There’s "zero evidence" that the new variant causes more severe disease, said Dr. Mike Ryan, executive director of the WHO’s Health Emergencies Programme.

The variant was reported to the WHO on Dec. 14. In the last few days, a number of countries have introduced travel bans to the United Kingdom.

The variant has also been identified in one patient in Australia, one in Iceland, one in Italy, one in the Netherlands, and believed to be in about 10 people in Denmark, Van Kerkhove said.

Studies around antibody response are underway. WHO officials said they expect results in the "coming days and the coming weeks."

ABC News’ Christine Theodorou contributed to this report.

Gov. Andrew Cuomo wants New York state added to the list of countries requiring United Kingdom travelers to get tested before flying in the wake of a new variant of the novel coronavirus linked to an uptick in cases in England.

"If 120 countries require testing ... why are we doing nothing?" Cuomo said.

"I know and I believe my intuition is correct that it is another disaster waiting to happen,” Cuomo said.

British Airways and Delta have agreed to the governor’s request to test passengers flying from the U.K. to New York, Cuomo said. Virgin Atlantic is considering the request, Cuomo said.

A number of countries have introduced travel bans to the U.K. France, Germany and several other European countries have suspended flights, while similar measures have been taken around the world -- as far as Canada and Hong Kong.

The number of new coronavirus cases and deaths jumped over the last seven days, according to an internal U.S. Department of Health and Human Services memo obtained by ABC News.

In the last week, the country recorded 1,677,232 new cases, which was a 13.6% increase from the previous seven-day period, according to the memo.

There were 18,578 deaths recorded during the last seven days, marking a 9.2% jump from the previous week, according to HHS.

Nearly 30% of hospitals across the country have more than 80% of their ICU beds filled, the memo said.

Several states recorded large jumps in hospitalizations last week, according to HHS.

On Dec 18, Louisiana state officials reported its 30-day increase in hospitalization was 82% and there were only 19.1% of ICU beds were available, according to the memo.

Nevada's COVID-19 deaths increased by 21% in the week ending Dec. 15, compared to the prior week, HHS said.

-ABC News' Josh Margolin contributed to this report