WARSAW, Poland (AP) — Hungarian doctors and health care workers began getting vaccinated Saturday with one of the continent's first shipments of the Pfizer-BioNTech vaccine against COVID-19, upsetting plans for a coordinated rollout on Sunday of the first shots across the 27-nation European Union.

The first shipments of coronavirus vaccines arrived across the bloc late Friday and early Saturday. It was not immediately clear why Hungarian authorities began their vaccinations a day early. Authorities in Slovakia also announced that they planned to begin administering their first doses on Saturday evening.

European Commission President Ursula von der Leyen released a video celebrating the vaccine rollout, calling it “a touching moment of unity.”

“Today, we start turning the page on a difficult year. The COVID19 vaccine has been delivered to all EU countries. Vaccination will begin tomorrow across the EU," she said.

In Hungary, the first shipment of 9,750 doses — enough to vaccinate 4,875 people, since two doses are needed per person — arrived by truck early Saturday and were taken to the South Pest Central Hospital in Budapest. The government said four other hospitals, two in Budapest and two others in the eastern cities of Debrecen and Nyíregyháza, would also receive vaccines from the initial shipment.

The vaccines developed by BioNTech and Pfizer arrived by truck in very cold conditions were delivered warehouses across the continent on Friday and early Saturday after being sent from a manufacturing center in Belgium before Christmas.

The rollout marks a moment of hope for a region that includes some of the world's earliest and worst-hit virus hot spots, including Italy and Spain, and others, like the Czech Republic, that were spared the worst early on only to see their health care systems near their breaking points in the fall.

Altogether, the 27 EU member states have seen at least 16 million cases of the coronavirus and more than 336,000 deaths.

“It’s here, the good news at Christmas," German Health Minister Jens Spahn said at a news conference Saturday. "This vaccine is the decisive key to end this pandemic.”

“It is the key to getting our lives back,” Spahn said.

The rollout is the result of coordination on the part of all 27 member states, helping the bloc to also project a sense of unity in a lifesaving mission of logistical complexity after difficulties in negotiating a post-Brexit trade deal with Britain.

The first doses, however, are limited just under 10,000 doses in most countries, with the mass vaccination programs expected to begin only in January.

Each country is deciding on its own who will get the first shots — but they are all putting the most vulnerable first.

French authorities said they will prioritize the elderly, based on the high impact on older populations in previous virus surges in France. The French medical safety agency will monitor for eventual problems.

Germany, where the pandemic has cost more than 30,000 lives, will begin with those over 80 and people who take care of vulnerable groups.

Spanish authorities said early Saturday that the first batch of the coronavirus vaccine to reach the country had arrived in the central city of Guadalajara — where the first shots will be administered on Sunday morning at a nursing home.

In Italy, which leads Europe in confirmed known deaths, a nurse in Rome at Spallanzani Hospital, the main infectious diseases facility in the capital, should be the first in the country to receive the vaccine, followed by other health personnel.

In Poland, the first two people to be vaccinated on Sunday will be a nurse and a doctor at the Interior Ministry hospital in Warsaw, the main coronavirus hospital in the capital, followed by medical personnel in dozens of other hospitals.

Prime Minister Mateusz Morawiecki recently called it the patriotic duty of Poles to get vaccinated — a message directed at a society where there is a high degree of vaccine hesitancy born from a general distrust of authorities.

In Bulgaria, where suspicions also run high, the first person to get the shot will be Health Minister Kostadin Angelov, who has promised an aggressive campaign to promote the benefits of the shots.

In Croatia, where the first batch of 9,750 vaccines arrived early on Saturday, a care home resident in Zagreb, the capital, will be the first to receive the vaccine on Sunday morning, according to state HRT TV.

HRT TV also reported that authorities would launch a pro-vaccination campaign that will include celebrities and other public figures getting the vaccine on camera.

“We have been waiting for this for a year now,” Romanian Prime Minister Florin Catu said on Saturday after the first batch of the vaccine arrived at a military-run storage facility there.

The vaccinations begin as the first cases of a new variant of the virus that has been spreading in the U.K. have now been detected in France and Spain. The new variant has caused several European countries to restrict traffic with Britain.

A French man living in England arrived in France on Dec. 19 and tested positive for the new variant Friday, the French public health agency said in a statement. He has no symptoms and is isolating in his home in the central city of Tours.

Meanwhile, health authorities in the Madrid region said they had confirmed the variant in four people, all of whom are in good health. Regional health chief Enrique Ruiz Escudero said that the new strain had arrived when an infected person flew into Madrid’s airport.

German pharmaceutical company BioNTech is confident that its coronavirus vaccine works against the new UK variant, but further studies are needed to be completely certain.

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Associated Press writers Lorne Cook in Brussels, David McHugh in Frankfurt, Germany, Angela Charlton in Paris, Joseph Wilson in Barcelona, Spain, Frances D'Emilio in Rome, Jovana Gec in Belgrade, Serbia, and Veselin Toshkov in Sofia, Bulgaria, contributed to this report.