BRUSSELS — European Union nations have officially kicked off a coordinated effort to give COVID-19 vaccinations to adults among their 450 million citizens, marking a moment of hope on the continent.

Shots were administered on Sunday morning to the most vulnerable people and health care workers across the bloc.

European Commission President Ursula von der Leyen said the mass roll-out of a viable coronavirus vaccine was "a touching moment of unity" for the union.

In Prague, Czech prime minister Andrej Babis received his shot at dawn and asserted: "There’s nothing to worry about".

In Rome, five doctors and nurses wearing white scrubs sat in a semi-circle at Rome’s Spallanzani infectious diseases hospital to receive their doses.

"Getting vaccinated is an act of love and responsibility toward the collective whole," Claudia Alivernini, a 29-year-old Spallanzani nurse, said on the eve of being the first to receive the shot in Italy, which has Europe's worth virus toll at more than 71,000 dead.

Italian Health Minister Roberto Speranza, speaking outside the hospital, said the coordinated EU rollout was a sign of hope for the continent, but that people still cannot let down their guard for several months more.

"We still have difficult months ahead," he said. "It’s a beautiful day, but we still need to exercise caution... this vaccine is the true path to close out this difficult season".

Germany, Hungary and Slovakia started their COVID-19 vaccination campaign on Saturday, a day earlier than the European Commission's planned coordinated roll-out across all member states.

EU member states each received a first shipment of just under 10,000 doses of the Pfizer/BioNtech vaccine on Saturday but vaccination was not supposed to start across the bloc's 27 nations until Sunday.

But Hungary's Minister for Human Resources, Miklos Kasler, said in a statement the vaccines had been delivered to the South-Pest Hospital Centre in Budapest and that healthcare workers had started receiving the jab.

"Today, we have taken an important step in curbing the epidemic," he added.

Austria began on Sunday the mass vaccination program to inject its people against COVID 19 a vaccine developed by US-based Pfizer partnered by BioNTech, a german biotechnology company, with the participation of Austrian Chancellor Sebastian Kurz.

A woman aged 84 was the first person in Austria to be vaccinated at the Medical University of Vienna, Austria Press Agency reported.

She said that after receiving the first dose, there was a bit of pain at the site of where she was pricked by the needle at the time it was given, underlining the the wanted to see her children and grandchildren.

Slovakia's Health Ministry said in a Facebook post on Saturday afternoon that "vaccination will begin in the faculty hospital in Nitra today".

Immunization also began in a German nursing home. “Every day that we wait is one day too many,” said Tobias Krueger, operator of a nursing home in Halberstadt, in the northeast region of Saxony-Anhalt.

It is unclear why both eastern countries started their vaccination campaign a day earlier than the European Commission's coordinated roll-out planned for.

In a video released on Twitter on Saturday, von der Leyen said that Europe "is starting to turn the page on a difficult year".

"Today is delivery day and tomorrow vaccination against COVID-19 is beginning across the European Union".

"Our European Vaccination Days are a touching moment of unity," she added, Euronews reported.

The Pfizer/BioNtech vaccine, which requires two shots, was approved by the European Medicines Agency (EMA) on Dec. 21.

The EU has secured up to 300 million doses through an Advance Purchase Agreement and expects for the first 200 million doses to have been delivered by September 2021.

But it has also struck similar deals with other pharmaceutical companies including Sanofi-GlaxoSmithKline, AstraZeneca, Janssen Pharmaceutica NV, CureVac, and Moderna.

These contracts mean the bloc "has secured enough doses of vaccines for our whole population of 450 million people," von der Leyen said in her video. The EMA is expected to decide whether to approve the Moderna vaccine on Jan. 6. — Agencies