(CNN) — For the third week in a row, the US Centers for Disease Control and Prevention did not add a single new destination to its highest-risk Level 4 category for travel.
In fact, seven destinations in Asia and the Caribbean moved to the CDC's lowest-risk category for travel during the pandemic, which is Level 1. Moving into that enviable ranking on Monday were island getaways the Philippines and Saint Kitts and Nevis.
But much of Europe -- including its popular travel powerhouses -- remained stubbornly lodged at Level 4.
Take the United Kingdom, for instance. It's been at Level 4 since July 19, 2021. That puts England, Scotland, Wales and Northern Ireland all in the "Very High" risk category for Covid-19.
The CDC designates a destination a Level 4 risk when more than 500 cases per 100,000 residents have been registered in the past 28 days.
CDC: Avoid Level 4 destinations
The Ha'penny Bridge is a signature symbol of Dublin, Ireland. Like almost all of Europe, Ireland is at the CDC's Level 4.
It's not just the United Kingdom. Many of the big names in Europe remain at Level 4 as winter lifts and the spring travel season begins. On April 11, that list included the following places:
• The Netherlands
However, it's not just Europe that has highly visited destinations stuck at Level 4 for now.
In Asia, Hong Kong, South Korea and Thailand are at Level 4. In South America, Brazil and Chile are still in the highest risk category. Same goes for the lush Central American getaway of Costa Rica. Other favorites awaiting a better grade from the CDC: Aruba, Australia and Bermuda.
Still, the general trend in risk level has been downward for much of the world in recent weeks, and Africa in particular has seen its risk assessments dropping.
In late February, the number of spots in Level 4 swelled to more than 140, illustrating the vast range and rapid spread of Omicron. But on April 11, that number shrank down to roughly 90 destinations. That's less than half of the approximately 235 places the CDC monitors.
The CDC advises avoiding travel to Level 4 countries. CDC thresholds for travel health notices are based primarily on the number of Covid-19 cases in a destination.
The CDC does not include the United States in its list of advisories, but it was color-coded at Level 3 on April 11 on the agency's map of travel risk levels. In its broader travel guidance, the CDC has recommended avoiding all international travel until you are fully vaccinated.
Few changes at Level 3
A view of the Old Town in the Red Sea coastal resort Sharm el-Sheikh. Egypt was placed at Level 3 by the CDC on Monday.
The Level 3 "High" risk category -- which applies to destinations that have had between 100 and 500 cases per 100,000 residents in the past 28 days -- saw just two additions on Monday. They were:
• Saint Martin
Both had previously been at Level 4.
People who want to take a trip to Europe but want to avoid the highest-risk destinations have only a few choices here: Albania, Bosnia and Herzegovina, and Kosovo, all on the Balkan Peninsula, or Armenia, in the mountainous Caucasus region.
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.
The sole new entry to Level 2 on April 11 is Guyana, a small nation in the northern part of South America that sees little in the way of international visitors. Guyana had been at Level 3.
Pinagbuyutan Island is just one representative of the many stunning oceanic spots in the Philippines. Travelers looking for a destination with a "Low" risk rating from the CDC have it here, though the rankings change weekly.
Igor Tichonow/Adobe Stock
In a hopeful sign for travelers, Level 1 saw the most movement.
To be in "Level 1: Covid-19 Low," a destination must have had fewer than 50 new cases per 100,000 residents over the past 28 days. Seven places moved to Level 1 on Monday:
• Saint Kitts and Nevis
• Saint Vincent and the Grenadines
• Saudi Arabia
The biggest moves belonged to Haiti, Myanmar and Saudi Arabia, which had been at Level 4. Saint Vincent and the Grenadines had been at Level 3, and the rest moved down from Level 2.
Most of the destinations in Level 1 are in Africa, including Ghana, Kenya, Morocco and Senegal.
Finally, there are destinations for which the CDC has an "unknown" risk because of a lack of information. Usually, but not always, these are small, remote places or places with ongoing warfare or unrest. The CDC made three additions to the category on Monday:
• Burkina Faso
• Faroe Islands
Burkina Faso had been at Level 1, and the other two at Level 4.
The Azores, Cambodia, Macau and Tanzania are among the locations currently listed in the unknown category. The CDC advises against travel to these places precisely because the risks are unknown.
A medical expert weighs in on risk levels
Transmission rates are "one guidepost" for travelers' personal risk calculations, according to CNN Medical Analyst Dr. Leana Wen.
"We are entering 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," Wen said in mid-February.
"You should interpret Level 4 to mean this is a place with a lot of community transmission of Covid-19. So if you go, there is a higher chance that you could contract the coronavirus," 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.
Some people will decide the risk is too high for them, Wen said. "Other people will say, 'Because I am vaccinated and boosted, I am willing to take on that risk.'
"So this really needs to be a personal decision that people weigh understanding that right now the CDC is classifying the different levels based on community transmission rates, and basically only that," Wen said. "They're not taking into account individual circumstances."
More considerations for travel
There are other factors to weigh in addition to transmission rates, according to Wen.
"The transmission rates are one guidepost," Wen said. "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.
"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.
People should be wearing a high-quality mask -- N95, KN95 or KF94 -- anytime they're in crowded indoor settings with people of unknown vaccination status, she said.
And it's also important to consider what you would do if you end up testing positive away from home. Where will you stay and how easy will it be to get a test to return home?