The US Centers for Disease Control and Prevention did not add any new destinations to its list of nations and territories with a "high" risk of Covid-19 on Monday.

However, locations at "high" risk -- designated as Level 3 -- still account for almost 130 of the roughly 235 places monitored by the CDC.

That's more than half of all places on the CDC site, and some of those destinations are among the most popular for tourists around the world.

Only one country, the sparsely populated desert nation of Namibia, dropped out of Level 3 to a lower risk rating this week.

Level 3 became the top rung in terms of risk level in April after the CDC overhauled its ratings system for assessing Covid-19 risk for travelers.

The designation applies to places that have had more than 100 cases per 100,000 residents in the past 28 days. Level 2 and Level 1 are considered "moderate" and "low" risk, respectively.

Relatively few places in the world are currently in Levels 2 or 1.

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. Under the new system, no destinations have been placed at Level 4 so far.

"Unknown" is for places from which the CDC didn't receive enough date to make an assessment.

More on Level 3
Much of Europe has been stubbornly lodged at Level 3 for months with the summer travel season now starting to wind down. The following popular European destinations were among those remaining at Level 3 as of August 22:

• France
• Germany
• Greece
• Ireland
• Italy
• The Netherlands
• Norway
• Portugal
• Spain
• United Kingdom

Those aren't the only high-profile spots that find themselves at Level 3. Numerous other destinations around the world are among those in the "high" risk category, including the following:

• Brazil
• Canada
• Costa Rica
• Malaysia
• Mexico
• South Korea
• Thailand
• Turkey

And Level 3 isn't limited to heavy hitters. Case in point: Saint-Pierre and Miquelon, a self-governing archipelagic territory of France situated off the southern coast of Newfoundland in Canada, and the French island department Réunion in the Indian Ocean, are also in this category.

The CDC advises that you get up to date with your Covid-19 vaccines before traveling to a Level 3 destination. Being "up to date" means you have had not only the full initial vaccinations but any boosters for which you're eligible.

Level 2
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.

The CDC added two destinations to Level 2 on Monday:

• Cuba
• Namibia

The move was bad news for Cuba, which had been at Level 1. Namibia dropped down from Level 3.

There are only 19 places listed at Level 2 this week. Some of the more-visited places in this category are India, Kenya and South Africa.

You can view the CDC's risk levels for any global destination on the agency's travel recommendations page.

In its broader travel guidance, the CDC recommends being up to date with your vaccines before traveling internationally.

Level 1
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. Only one new place was added to the category on August 22: Saudi Arabia, which had been at Level 2.

Just 22 places were in the "low" risk category this week. A few of the more popular places with world travelers in the "low" risk category this week included Egypt and Tanzania.

Unknown
Finally, there are the destinations the CDC has deemed to be of "unknown" risk because of a lack of information. Usually, but not always, these are small, remote places or places with ongoing warfare or unrest.

One new destination was added this week: The small West African nation of Benin, which had been at Level 1.

The CDC advises against travel to these places precisely because the risks are unknown. Other destinations in this category that typically draw more tourist attention include Hungary, the Maldives and Vietnam.

There are almost 70 places listed as "unknown" this week, making up almost one-third of all the places monitored.

A medical expert weighs in on risk levels
Transmission rates are just "one guidepost" for travelers' personal risk calculations, according to CNN Medical Analyst Dr. Leana Wen.

We've moved into "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," 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.

There are other factors to weigh in addition to transmission rates, according to Wen.

"Another is what precautions are required and followed in the place that you're going and then the third is what are you planning to do once you're there," she said.

"Are you planning to visit a lot of attractions and go to indoor bars? That's very different from you're going somewhere where you're planning to lie on the beach all day and not interact with anyone else. That's very different. Those are very different levels of risk."

Vaccination is the most significant safety factor for travel, since unvaccinated travelers are more likely to become ill and transmit Covid-19 to others, Wen said.

And it's also important to consider what you would do if you end up testing positive away from home.

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 recently.