Since the start of August, nine COVID-19 patients under 40 have died in Montenegro and not one was vaccinated, the country's public health institute said on Sunday.
Montenegro is again among the countries with the highest number of daily infections.
Most of the patients are aged 30-39 and this group is also the least vaccinated, the institute said.
Epidemiologists said 86.5% of those who died since early May, when mass immunisation began, were not vaccinated and that over 90% of those hospitalised and ill were also not vaccinated.
Montenegro has vaccinated 45% of its adult population.
In two months, the number of infections has jumped from less than 500 to over 8,000, ranking Montenegro third in the world according to the number of cases per million population, an average of 995.6 per day.
Last week Montenegro closed its borders for everyone who has not been vaccinated, does not have a COVID certificate or a negative test.