The German government has placed the United States, Turkey, and Israel as high-risk countries.
Montenegro and Vietnam are also affected by the upgrade.
Portugal has been downgraded and is no longer a high-risk area, with the exception of Lisbon and the Algarve, according to the FUNKE media group that reported citing government sources.
Travelers from high-risk countries must go into quarantine for ten 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.