Authorities in southwestern Spain have issued an international health alert to locate a group of Dutch tourists who fled a hotel where they were meant to isolate for 10 days after testing positive for coronavirus. Police were searching for the tourists and airports were also on full alert in case they try to leave the country.

Charo Espino, a spokeswoman for the health department in the Extremadura region, said that seven of nine of the tourists from the Netherlands who had tested positive for COVID-19 had simply “disappeared.”

The group was travelling through Extremadura when some of them felt sick and stopped in Navas del Madroño, a town halfway between the regional capital, Cáceres, and the border with Portugal, for a test that confirmed their contagion, local councillor Denis Talavera told Extremadura TV.

“The tourists were staying at a local hotel and they had to keep the quarantine mandated by health authorities, but they didn’t,” Talavera told the regional public broadcaster. “We don’t know how or when they left,” he added.

A slight increase in new coronavirus infections has brought Spain’s 14-day contagion rate over 100 new cases per 100,000 residents. Although that’s still a far cry from the sharp spikes recorded in other European countries, some regional governments have approved, or are mulling, the use of mandatory “vaccine passports” to enter indoor public spaces, restaurants, or nightclubs.

After hard-hitting COVID-19 waves in 2020 and early 2021 that killed thousands and strained the country’s hospitals, Spain has fully vaccinated 89% of residents aged 12 or older.

Spain, which has one of Europe’s highest vaccination rates, is readying more measures to deal with a recent uptick in new coronavirus infections just over one month away from a busy travel period for end-of-the-year family reunions.

Last week, the government announced plans to widen the use of booster shots to people over 60 years, from 70 and older until now.