The German government has designated the United States, Turkey, and Israel as high-risk countries, triggering a minimum five-day quarantine requirement for those who are unvaccinated, the Funke media group reported Friday citing government sources.

Montenegro and Vietnam are also affected by the upgrade, while Portugal has been downgraded and is no longer a high-risk area, with the exception of Lisbon and the Algarve, Funke said.

The upgrade will take effect on Sunday, except in the case of Turkey where it will come into force on Tuesday night given the large number of people in Germany with a Turkish background, Funke said, citing government sources.

Travelers from high-risk countries must quarantine for 10 days unless they can show proof of vaccination or recovery from COVID-19. Self-isolation can be ended after five days at the earliest with a negative test.

Germany had in June removed Turkey from the list as daily coronavirus infections dropped, but an upward trend in recent weeks likely prompted the move.

Turkey has long been a top destination for German holidaymakers but the arrivals fell sharply last year due to virus-related travel restrictions and quarantine measures.

Over half a million Germans have arrived in Turkey from January through June this year, according to official data.