There have been 144 confirmed coronavirus infections, most likely with the Delta variant, among Slovenian high school seniors who have recently returned from their graduation trips in Spain, and about a hundred people they have been in contact with are in isolation, health authorities said on Monday.

Epidemiologist Eva Grilc of the Slovenian National Institute of Public Health told local media that a group of students from the Dolenjska region had stayed at the Catalan resort of Lloret de Mar, while another group was from Gorenjska region. Each group consisted of over 300 senior students.

“Most of the infected are without symptoms and have been sent to quarantine, while self-isolation has been recommended also to those who tested negative,” Grilc said.

She added that it was suspected they were infected with the Delta variant which was spreading across Spain and some other European countries.

Two persons who have been in contact with the infected did not stay in isolation and went to Croatia, about which Croatian epidemiologists have been informed, so they have been sent to quarantine there, Grilc said.

According to her, most Slovenian high school seniors went abroad unvaccinated, so she recommended that young people get vaccinated against Covid-19 before going on a trip now that there is enough vaccine.

On Monday, Slovenia logged 12 new infections and two deaths. Thirty-five percent of the population have received both vaccine doses, while 40% received one.