The Centers for Disease Control and Prevention (CDC) and the State Department warned Monday against U.S. travel to Germany and Denmark amid rising COVID-19 infections.
The countries were all marked by the CDC as "Covid-19 Very High" in the Level 4 category.
Now, a total of 75 places in the world are part of that list, which means they had more than 500 coronavirus cases per 100,000 people for each of the past 28 days.
"Avoid travel to these destinations. If you must travel to these destinations, make sure you are fully vaccinated before travel," the CDC's website says.
"Do not travel to Germany due to COVID-19," the State Department, which also designated the countries as "Level 4: Do Not Travel," added. The department issued the same notice for Denmark.
German Health Minister Jens Spahn has said that unvaccinated people are likely to catch COVID-19 by the end of this winter season, adding that some of them will die.
Germany has seen a 50 percent increase in new coronavirus infections in the past week.
It now has a daily case average of more than 49,000, according to The New York Times.
As Germany's cases spike, older people who were among the first to receive both doses of the coronavirus vaccine and children who are not eligible for vaccination are particularly susceptible to the virus, Reuters reported.
Just last week, the Czech Republic, Hungary, Iceland and the island of Guernsey were also added to the Level 4 category.
The travel advisories come after the U.S. reopened its borders to international travelers earlier this month following months-long COVID-19 travel restrictions. Under this new policy, fully vaccinated international travelers are permitted to enter the U.S. provided they show proof of vaccination and a negative COVID-19 test taken within three days of their trip.