(CNN) — The alpine nation of Austria and the Caribbean island of Barbados were deemed “very high” risk travel destinations on Monday by the US Centers for Disease Control and Prevention.

The two locations join four other new additions to the Level 4 category on the CDC’s regularly updated list of travel advisories.

Destinations that fall into the “Covid-19 Very High” Level 4 category have had more than 500 cases per 100,000 residents in the past 28 days, according to CDC criteria.

People should avoid traveling to locations designated with a “Level 4” notice, the CDC recommends. Anyone who must travel should be fully vaccinated first, the agency advises. More than 80 destinations are now listed as Level 4.

All the destinations that moved to Level 4 this week were previously listed as “Level 3: Covid-19 High.” The Level 3 category applies to destinations that have had between 100 and 500 cases per 100,000 residents in the past 28 days.

The CDC’s travel notices range from Level 1 (“low”) to Level 4 (“very high”). The CDC does not list the United States in its travel advisories.

These are the destinations added to Level 4 on October 4:

• Armenia
• Austria
• Barbados
• Croatia
• Latvia
• New Caledonia

New Level 3 locations

Eight locations this week moved into the lower risk Level 3 category from Level 4. The popular European destinations of France and Portugal are among those spots deemed less risky this week, according to CDC criteria.

The following destinations moved down to Level 3 on October 4:

• Argentina
• France
• Iceland
• Lesotho
• Morocco
• Nepal
• Portugal
• South Africa

For the second week in a row, the Caribbean island of Saint Barthelemy moved down into a lower risk category, this week from Level 3 to Level 2. Peru also received a Level 2 designation on Monday.

Destinations carrying the “Level 2: Covid-19 Moderate” designation have seen 50 to 99 Covid-19 cases per 100,000 residents in the past 28 days.

In “Level 1: Covid-19 Low” destinations, fewer than 50 new cases per 100,000 residents have been logged over the past 28 days.

You can view the CDC’s risk levels for global destinations on its travel recommendations page.

In its broader travel guidance, the CDC has recommended avoiding all international travel until you are fully vaccinated.

“Fully vaccinated travelers are less likely to get and spread Covid-19. However, international travel poses additional risks, and even fully vaccinated travelers might be at increased risk for getting and possibly spreading some Covid-19 variants,” the agency said.

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