(CNN) — Turkey and Montenegro are now among the highest-risk destinations for travelers, according to the US Centers for Disease Control and Prevention's regularly revised travel advisories list.
Travel should be avoided to locations carrying the "Level 4: Covid-19 very high" notice, according to CDC guidance. Anyone who must travel should be fully vaccinated first, the agency advises.
The CDC's evolving list of travel notices ranges from Level 1 ("low") to Level 4 ("very high").
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 parameters. The Level 3 category applies to destinations that have had between 100 and 500 cases per 100,000 residents in the past 28 days.
Turkey and Montenegro were previously ranked at "Level 3: Covid-19 high."
The Caribbean island of Dominica was listed before the update as a low-risk, Level 1 destination.
On the Island of Jersey, a British Crown dependency, Covid-19 levels were previously listed as "unknown" by the CDC. On August 16, the Island of Jersey's government site listed a 14-day rate of 452 cases per 100,000 population, with cases shown declining in recent weeks. The site does not list a 28-day case number.
New 'Level 3' destinations
Five destinations on Monday moved to the "Level 3: Covid-19 high" category: Chile, Mozambique and Uruguay (all moving down from Level 4), as well as Kosovo and North Macedonia (both moving up from Level 2).
CDC guidance for Level 3 destinations urges unvaccinated travelers to avoid nonessential travel to those locations.
In its wider travel guidance, the CDC recommends against 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.