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 U.S. is now averaging 2,613 new coronavirus-related deaths per day -- more than triple the seven-day average from two months ago, according to ABC News’ analysis of data compiled by the COVID Tracking Project.

So far this month, 49,752 Americans have died from COVID-19, according to the COVID Tracking Project.

In the last seven days, there have been approximately 18,000 deaths recorded -- equaling approximately 108 American deaths reported every hour.

In the week ending Dec. 19, 16 states hit a record number of new deaths: Alabama, Arizona, California, Delaware, Kansas, Kentucky, Missouri, Nevada, New Hampshire, North Carolina, Oregon, Rhode Island, Tennessee, Virginia, Washington and West Virginia.

ABC News’ Arielle Mitropoulos contributed to this report.