Only 26.4% are fully vaccinated.
Bulgaria has the lowest COVID vaccination rate in the European Union - just 26.4% are fully inoculated.
Logistical issues, political instability and distrust in public institutions are cited as being among the factors hampering vaccinations efforts.
Almost every week protesters gather in the streets of the capital Sofia to demonstrate against COVID vaccines and health passes.
"These vaccinations are like history repeating itself," a man who refuses to take the vaccine told Euronews. "Like in the era of World War II and the Jews. But this time everybody is a Jew. If you are not vaccinated, people start hating you."
"Manufacturers are saying vaccines will remain experimental until 2023/2024. I don't wish to be part of an experiment," another woman added.
Bulgaria's deputy health minister Aleksandar Zlatanov blames the poor vaccination rate on logistical issues and on political instability, due to the Balkan nation going through three parliamentary elections in just eight months.
But, he claims, things are slowly improving.
"The vaccination rate is now three times higher than in August. We expect this rate to increase four- or fivefold from now until the end of December," Zlatanov said.
In one of the Bulgarian capital's most active vaccination centres, the average number of people getting the vaccine these days is around 700. The vaccination centre has the capacity to vaccinate up to 2,000 people a day.
"I need to take care of myself. It is in my own interest. This is my third dose. I'm not afraid of the vaccine," revealed a woman getting the jab.
"Getting vaccinated is not compulsory but it is needed. It's the only defence we've got. It is needed for me and for others too. That's what I think," a man went on.
But with a far-right party just entering the new Parliament with an open anti-vaccination programme, will the figures still keep up?
As countries across Europe push for people to get their booster jabs, Bulgaria still has a lot of work to do to catch up.