Sri Lanka has been added to a list of places US travellers should avoid, while the UAE has had its risk status lowered.
The US Centers for Disease Control and Prevention added Sri Lanka, Jamaica and Brunei to its Level 4 category, which denotes that a place has a "very high" Covid-19 risk. Americans are advised not to travel to these destinations on the CDC's list.
The authority also downgraded the risk level for the UAE and three other destinations, moving the countries from Level 4 to Level 3, which means a place has a "high" Covid-19 risk.
"Avoid travel to Sri Lanka," states the CDC. "Because of the current situation in Sri Lanka, even fully vaccinated travellers may be at risk for getting and spreading Covid-19 variants."
Sri Lanka is battling rising case numbers of the coronavirus with a new record of 11,366cases on September 5.
The island destination is typically popular with holidaymakers from around the world thanks to its seemingly endless beaches, lush tree plantations and timeless ruins.
But the global pandemic has crushed the country's tourism industry, with revenue falling to about $2 million a month this year, compared to more than $450 million two years ago, according to data from Trading Economics.
The new additions to the Level 4 list mean there are now a total of 77 destinations, including Saudi Arabia, Kuwait, the Maldives and the UK.
To be ranked as a Level 4 risk category, countries must have registered more than 500 cases of the coronavirus per 100,000 residents in the past 28 days.
UAE Covid-19 risk level downgraded by CDC
The UAE was among a handful of countries where the CDC eased its ratings from Level 4 to Level 3, which denotes a "high" risk level. The Netherlands, Malta and Guinea-Bissau followed a similar change in status.
Australia conversely has been changed from a Level 1 country, which suggests a "low" risk of Covid-19, to a Level 2 destination, meaning the risk is now considered "moderate" by the health authority.
Guidance from the CDC recommends that, as a whole, US citizens and residents should not travel internationally unless they have received both doses of a Covid-19 vaccine.