(CNN) — The US Centers for Disease Control and Prevention on Monday moved three tropical island getaways and one Middle Eastern nation into its "moderate" risk category for Covid-19. There were no new additions to its "high" risk category this week.
The four new places now at "moderate" risk, or Level 2, are:
• Fiji (in the South Pacific)
• Kuwait (Middle East)
• Saint Kitts and Nevis (Caribbean)
• Sint Maarten (Caribbean)
Previously, Dutch Sint Maarten had been listed as "Unknown," which happens when the CDC doesn't have enough data to make a risk assessment. The other three places dropped down from "high" risk, or Level 3.
Just over half of the destinations monitored by the CDC are still listed in Level 3. That includes very popular tourism spots such as Brazil, France, Mexico and Thailand.
The designation applies to places that have had more than 100 cases per 100,000 residents in the past 28 days.
Destinations carrying the "Level 2: Covid-19 Moderate" designation reported 50 to 100 Covid-19 cases per 100,000 residents in the past 28 days.
To be listed as "Level 1: Covid-19 Low," a destination must have had 49 or fewer new cases per 100,000 residents over the past 28 days.
This week, four nations in Africa were placed in Level 1:
• Cape Verde
Level 4, previously the highest risk category, is now reserved only for special circumstances, such as extremely high case counts, emergence of a new variant of concern or health care infrastructure collapse. The CDC advises against traveling to these destinations. Under the new system, no destinations have been placed at Level 4 so far.
A medical expert weighs in on risk levels
The CDC advises travelers to get up to date with Covid-19 vaccines before traveling internationally. Being "up to date" means you have had not only the full initial vaccinations but any boosters for which you're eligible.
We're in "a phase in the pandemic where people need to make their own decisions based on their medical circumstances as well as their risk tolerance when it comes to contracting Covid-19," according to CNN Medical Analyst Dr. Leana Wen.
Vaccination is the most significant safety factor for travel, said Wen, who is an emergency physician and professor of health policy and management at the George Washington University Milken Institute School of Public Health.
"Most people who are up-to-date on their vaccines are highly protected from becoming severely ill," she said.
Consider what you would do if you end up testing positive away from home, Wen advised.
"Do you have access to treatments such as antiviral pills or monoclonal antibodies? Ask your doctor in advance of your trip whether you are eligible, then know where to find these treatments when traveling abroad," she said.
Wen also advises packing extra coronavirus tests and bringing them with you on your trip.
While US-bound travelers no longer have to present a negative Covid-19 test to get home from international destinations, the CDC still advises testing before boarding flights back to the States and not traveling if you are sick. "Of course, if people have symptoms or exposure while traveling, they need to get tested, and if they test positive, to follow CDC's isolation guidelines," Wen told CNN Travel. If you're concerned about a travel-specific health situation not related to Covid-19, check here.