(CNN) — The US Centers for Disease Control and Prevention moved three high-profile destinations to its highest-risk Level 4 category for travel on Monday.
Hong Kong and New Zealand have spent much of the pandemic in near isolation with relatively few infections and had been lauded as Covid success stories. However, the Omicron variant has caused massive spikes in cases in both places.
Hong Kong is late in playing out a now-familiar scene: Morgues near capacity, hospitals overwhelmed and supermarkets stripped bare by shoppers. Hong Kong has tightly restricted travel since the start of the pandemic and recently suspended many incoming international flights. The spike comes in New Zealand just as it is beginning to shift toward plans to open up its borders to select international vacationers later this year. It has maintained some of the strictest isolation measures in the world during the pandemic. While cases in New Zealand have recently spiked sharply, the country had logged only 65 deaths over the course of the pandemic as of early March, according to Johns Hopkins University figures.
New Zealand has seen a steep rise in Covid cases recently. However, as of early March, the country had logged only 65 deaths over the course of the pandemic.
Joining those two is Thailand, one of the crown jewels of world travel and the No. 1 Asian earner of tourism revenue in 2019. Thailand restarted its "Test & Go" program on February 1, which allows vaccinated international travelers from all countries to enter without lengthy quarantines.
The CDC places a destination at "Level 4: Covid-19 Very High" risk when more than 500 cases per 100,000 residents are registered in the past 28 days.
To recap, the destinations added to Level 4 on March 7 are:
• Hong Kong
• New Zealand
All three destinations were previously listed at Level 3, considered "high" risk.
Global case numbers have been declining since peaking in late January, but experts caution that the pandemic is not over.
CDC: Avoid Level 4 destinations
London is an international tourism favorite and the largest city in the United Kingdom, which has been at Level 4 since last summer.
Adrian Dennis/AFP/Getty Images
There are about 135 destinations currently at Level 4. While the number of places in the "very high" risk category has dipped slightly since topping around 140 in February, there are still more places in the Level 4 category than in all the other categories combined.
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 4 on March 7 on the agency's map of travel risk levels.
Other tourist favorites stalled on Level 4 include Canada, Egypt, France, Greece, Peru and Singapore. The United Kingdom has been there since July 2021.
In its broader travel guidance, the CDC has recommended avoiding all international travel until you are fully vaccinated.
Changes at Level 3
Mexico, with Bahia Principe beach in Tulum pictured here, moved down from Level 4 to Level 3 on Monday.
Rodrigo Arangua/AFP via Getty Images
Tourists looking for some news that's trending in a good direction will find it on this level.
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 six additions from various spots around the globe on Monday. They were:
• Cape Verde
• United Arab Emirates
All six had previously been at Level 4. Mexico has stayed open to tourists throughout the pandemic. It doesn't have any vaccination or testing requirements to enter.
Levels 2, 1 and unknown
On Monday, there was good news for people who are dreaming of a trip to Africa.
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. Nine destinations representing all sections of the continent moved to Level 2 on March 7:
• Equatorial Guinea
• The Gambia
Last week, all of these destinations were at Level 3.
Africa continued to be a bright spot with the Level 1 category as well, including the popular safari and cultural favorite Kenya.
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. Eight places moved to Level 1 on Monday:
• Côte d'Ivoire (Ivory Coast)
• Republic of Congo
The only destinations now listed at Level 1 outside of Africa are China and Taiwan.
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 no new additions to the category on Monday.
Tanzania, Cambodia and Macau are among the more-visited 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."