The coordinated rollout launched on Sunday is getting underway less than a week after the EU cleared a shot developed by Pfizer Inc. and BioNTech SE. Several European countries, including Germany, have imposed tougher restrictions in an effort to contain a winter surge in infections and deaths.

It will take months to inoculate enough people to have an impact on the spread of the disease, but the sense of urgency has grown after neighboring Britain locked down parts of the country, blaming a faster-spreading strain.

“Once enough people have been vaccinated, we can start traveling, meeting our friends and family again and have normal holidays, which we all long for,” European Commission President Ursula von der Leyen said Saturday in a video message.

The head of the EU’s executive arm was marking what she called “Delivery Day,” when doses of the vaccine were sent out across the continent. She emphasized that immunization will be a gradual process and caution is still needed.

“We have to continue being careful,” she said. “We have to protect ourselves and our loved ones.”

Weeks behind

Europe is starting the campaign to inoculate its 450 million citizens weeks after the U.K. and U.S. began their own vaccination programs. More than 600,000 people in Britain and nearly 2 million in the U.S. have received their first shot of the standard two-dose regimen, according to data collected by Bloomberg.

Despite the agreed EU rollout date, some nations, including Germany and Hungary, already began administering vaccines on Saturday, local media reported.

In the eastern German city of Halberstadt, a 101-year-old woman and around 40 others in a care home for the elderly were inoculated, according to DPA. “Every day we wait is a day too many,” the news agency quoted the head of the home, Tobias Krueger, as saying.

The start of the EU’s vaccination campaign comes amid an effort to contain the mutant virus strain that the U.K. government said is spreading more easily.

While that’s spurred concern that testing, treatments and shots might not be as effective, officials at BioNTech and the European medicines regulator said they’re optimistic the vaccine will work against the new strain. The variant has appeared in countries including Germany, Japan, Australia, Singapore and Italy.

The EU has ordered 200 million doses of the Pfizer-BioNTech shot on behalf of member states, with an option to obtain 100 million more, and the goal is to provide access to all countries at the same time on the basis of population size. Supplies will be limited in the early days, although another vaccine may soon help bolster availability.

The rollout will unfold gradually. The EU may have enough vaccine for two-thirds of its population in the middle of September, three months behind the U.S., according to London-based research firm Airfinity Ltd.