After more than six months in the US Centers for Disease Control and Prevention's lower-risk Level 3 travel category, Mexico moved into “very high” risk Level 4 on Monday along with 11 other destinations.

Tourism powerhouse Mexico had been listed at Level 3 since June 7. A record-high number of new Covid-19 cases has been recorded this month in Mexico.

Among the 12 destinations added to Level 4, five were in South America: Brazil, Chile, Ecuador, Paraguay and French Guiana (an overseas territorial collectivity of France).

In the Caribbean, Anguilla and Saint Vincent and the Grenadines moved into Level 4.

Singapore and the Philippines in Southeast Asia also moved into the highest-risk category, as did Moldova and Kosovo in Europe.

The CDC places a destination at Level 4 when more than 500 cases per 100,000 residents are registered in the past 28 days. The CDC advises travelers to avoid travel to Level 4 countries.

To recap, the 12 places added this week are:

• Anguilla

• Brazil

• Chile

• Ecuador

• French Guiana

• Kosovo

• Mexico

• Moldova

• Paraguay

• The Philippines

• Saint Vincent and the Grenadines

• Singapore

Nearly every addition to Level 4 was listed at Level 3 last week, or "high" risk for Covid-19. The only exception is French Guiana, which was listed as “unknown” last week because of a lack of information.

The Level 4 list now contains almost 130 places. In early January, there were around 80 destinations, demonstrating the rapid rise of the Omicron variant around the world. Level 4 now has more destinations than all the other CDC categories combined.

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

The CDC does not include the United States in its list of advisories, but it was color-coded at Level 4 on January 31 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.

Level 3 additions

The Level 3 category – which applies to destinations that have had between 100 and 500 cases per 100,000 residents in the past 28 days – saw 11 additions on Monday:

• Bhutan

• Brunei

• Comoros

• French Polynesia

• The Gambia

• Guinea

• Guinea-Bissau

• Honduras

• Liberia

• Nepal

• Oman

No destinations moved down from Level 4 this week. Six were previously at Level 2: Brunei, Comoros (an archipelago off the coast of East Africa), Guinea-Bissau, Honduras, Liberia and Nepal.

Bhutan, Guinea, The Gambia and Oman moved up two risk levels from Level 1.

Last week, French Polynesia was listed in the “unknown” category.

Levels 2, 1 and unknown

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.

There were no additions to Level 2 on Monday. Currently, there are just seven destinations at Level 2, including New Zealand, which has some of the world's tightest travel restrictions.

To be in “Level 1: Covid-19 Low,” a destination must have fewer than 50 new cases per 100,000 residents over the past 28 days.

No destinations were moved to Level 1 on Monday. There are currently eight destinations in the category, including China, which is hosting the Winter Olympic Games in February.

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. There were no additions this week.

Tanzania, Cambodia and the Canary Islands are among the locations currently listed in the unknown category. The CDC advises against travel to these places precisely because the risks are unknown.

Cruising

The CDC includes cruise ships on its destinations list.

On December 30, the CDC increased the risk for cruise ship travel to Level 4 and said it should be avoided, regardless of vaccination status. It remained at Level 4 in the newest update.

Meanwhile, the CDC's Covid-19 guidance has become optional for many cruise ships.

The CDC’s extended conditional sailing order expired recently, and the agency has transitioned to a voluntary program for foreign-flagged cruise ships operating in US waters.

Considerations for travel

Transmission rates are important to consider when making travel decisions, but there are other factors to weigh as well, according Dr. Leana Wen, a CNN medical analyst, emergency physician and professor of health policy and management at the George Washington University Milken Institute School of Public Health.

“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.

She 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.

Before you travel, it’s also important to consider what you would do if you end up testing positive away from home, Wen said. Where will you stay and how easy will it be to get a test to return home? (CNN)

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