Greece and a handful of other European Union members began vaccinating children ages 5-11 against COVID-19 on Wednesday as governments braced for the holiday season and the spread of the omicron variant.

An Athens children’s hospital administered its first shots to younger children hours after authorities announced Greece’s highest daily death of the pandemic at 130. The children were given stickers and the day off school.

More than 30,000 vaccination appointments for under-12s have been booked by Greek parents, among them Education Minister Niki Kerameus.

“I won’t hide the fact that on a personal level, after having talked with doctors and receiving scientific data, our family decided to vaccinate our son who is 5 1/2 years old,” Kerameus said before taking her son, Loukas, to get his shot at an Athens hospital.

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Italy, Spain and Hungary also expanded their vaccination programs to younger children. European Union regulators last month approved a reduced-dose vaccine made by Pfizer-BioNTech for use in the 5-11 age group.

A two-month surge in infections across Europe eased slightly in early December, but the appearance of the omicron variant has created uncertainty. Scientists think omicron is highly contagious, but they are not yet sure how dangerous it is.

The European Center for Disease Prevention and Control said Tuesday that it expects omicron to dominate infections in the EU within the next few months. It suggested that governments consider travel-related restrictions and press ahead with vaccination campaigns and booster shot delivery.

Vaccines for children are voluntary in all European Union countries and require parental approval.

Authorities in Spain have set ambitious targets for vaccinating younger children before Christmas and the customary family gatherings. Nearly 90% of the country’s residents age 12 and older have received two vaccine doses.

Poland, Portugal, Croatia and Slovenia plan to lower their vaccine eligibility age later in the week.

Several hundred people protested Wednesday in front of the government headquarters in Croatia’s capital, Zagreb, Wednesday. The protesters chanted “Don’t kill our kids” and “We won’t give you our children.”

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Other EU nations are taking a cautious approach to vaccinating younger children. Germany has started a region-based rollout, the Netherlands is waiting until after the holidays, and France is prioritizing children who suffer from heart and respiratory problems, obesity, and diabetes.

Britain was slower than many European countries to start vaccinating children ages 12-15, and it has not yet approved vaccines for younger children.

Wei Shen Lim, a member of the U.K.’s Joint Committee on Vaccination and Immunization, said the group expected to make a decision before Christmas but was awaiting a recommendation from British regulators.

Conservative lawmaker Jeremy Hunt, a former health minister, criticized the delay. “Our regulators, having been the nimblest in the world, are now taking too long,” he said.