The Centers for Disease Control and Prevention (CDC) added four more destinations to its highest risk category for travel as COVID-19 surges impact Europe.
The Czech Republic, Hungary, Iceland and Guernsey were all added to the CDC's "Covid-19 Very High" Level 4 category.
Level 4 categorization means that these countries or destinations had more than 500 cases of COVID-19 per 100,000 people for each of the past 28 days. The island of Guernsey, a channel island between Great Britain and France, has less than 100,000 residents. It received the designation because it had more than 500 cumulative new cases over 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 U.S. agency's website said of the destinations.
The Czech Republic has a daily case average of nearly 11,000 infections.
Hungary's daily new cases hover around an average of 7,200 while Iceland's was at just 167, according to The New York Times. Guernsey's government reported that the island currently had over 400 active COVID-19 cases.
As of this week, over 80 destinations are listed in the highest risk category. The agency also recommends getting fully vaccinated and masking on transportation while traveling regardless of one's destination.
The designation comes as the U.S. just opened its borders to international travelers earlier this month after more than 18 months of COVID-19 travel restrictions. Under this new policy, fully vaccinated international travelers are permitted to enter the U.S. as long as they provide proof of vaccination and show a negative COVID-19 test that was taken within three days of travel.