VELIKO TARNOVO, BULGARIA -- Standing outside the rundown public hospital in Bulgaria's northern town of Veliko Tarnovo, the vaccination unit's chief nurse voices a sad reality about her fellow citizens: "They don't believe in vaccines."

Bulgaria has one of the highest coronavirus death rates in the 27-nation European Union and is facing a new, rapid surge of infections due to the more infectious Delta variant. Despite that, people in this Balkan nation are the most hesitant in the bloc to get vaccinated against COVID-19.

Only 20% of adults in Bulgaria, which has a population of 7 million, have so far been fully vaccinated. That puts it last in the EU, which has an average of 69 % fully vaccinated.

"We are open every day," Yordanka Minekova, the chief vaccination nurse who has worked at the hospital for 35 years, told The Associated Press. "But people who want to be vaccinated are very few."

Krasimira Nikolova, a 52-year-old restaurant worker, has chosen not to get vaccinated, saying she has doubts over the effectiveness of the available vaccines.

"I don't believe vaccines work," she told the AP. "Hospitals are full of people who are vaccinated ... I already had the virus. I don't believe it's so dangerous. I have other health issues and if it was that dangerous, I would probably be dead already."

But Sibila Marinova, manager of Veliko Tarnovo's intensive care unit, says all 10 beds in its COVID-19 ICU ward are occupied and she feels angry that so many Bulgarians are refusing to get jabbed.

"100% of the ICU patients are unvaccinated," she told the AP, adding that staff shortages are only piling on more pressure.

Bulgaria has access to all four of the vaccines approved by the EU -- Pfizer, Moderna, AstraZeneca, and Johnson&Johnson. But since the start of the pandemic, more than 19,000 people in Bulgaria have died of COVID-19, the EU's third-highest death rate, behind only the Czech Republic and Hungary. In the last week, an average of 41 people have died each day.

Bulgaria's largely failed inoculation campaign now risks putting the country's ailing health care system under serious strain.

In response, the government imposed tighter restrictions Tuesday. Restaurants and cafes must close at 11 p.m. and their tables are limited to six people. Nightclubs have been shuttered and cinemas and theatres are limited to half capacity. Outdoors sports arenas are limited to 30% capacity.

"The low vaccination rate forces us to impose these measures," Health Minister Stoycho Katsarov said.

Despite being in a vulnerable age group, 71-year-old retiree Zhelyazko Marinov doesn't want to get vaccinated.

"I think I'm healthy enough and have a good natural immunity," he said.

He gets most of his information about the vaccines from TV and Facebook, but said he could be persuaded to get vaccinated.

"If I were deprived of some rights and freedoms, I would get vaccinated," he said. "For example, if I cannot travel without a vaccine certificate."

Mariya Sharkova, a public health law specialist, believes that Bulgaria's worryingly low vaccine uptake is the result of residents' low trust in official institutions, along with fake news about the shots, political instability and a weak national vaccination campaign.

"In Bulgaria, we don't have good health literacy," she told the AP. "Many people choose to believe conspiracy theories and fake news."

Only vaccines that are mandatory in Bulgaria -- such as measles, mumps and rubella -- have a high uptake. Sharkova said some blame has to lie with the government's vaccination program.

"They didn't build any strategy on how to fight vaccine hesitancy," she said. "We didn't have any real information campaign for the vaccines. The ministry of health relies mainly on announcements on the ministry's website, and I don't think anyone actually goes on and reads it."

"The best policy for such hesitant countries and populations as ours are mandatory vaccines," said Sharkova, who is dismayed that national TV channels often invite vaccine-skeptic doctors to be on their programs.

But making COVID-19 vaccines mandatory could risk further polarizing the issue, she said.

Hriska Zhelyazkova, a 67-year-old military officer from the coastal city of Burgas, says she distrusts vaccines because "they were created so quickly."

"I think my body would do well if I contracted the virus," she said. "I get information from the internet, (and) read the opinions of virologists."

Still, she said she may get vaccinated if authorities slap tougher restrictions on unvaccinated people.

Back at the Veliko Tarnovo hospital, pro-vaccination drawings colored by children hang on the walls. "You are our superheroes," one caption read.

But Minekova, the vaccination nurse, isn't optimistic about the future.

"Somehow, I think it's too late," she said. "The right moment has been missed. I don't see a way right now to solve this."

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Valentina Petrova contributed to this report from Burgas.