The Centers for Disease Control and Prevention (CDC) added 22 countries to its advisory list against travel on Tuesday.
The countries were added to the highest warning level, level 4, due to the rising cases of COVID-19.
Some of the countries added include Israel, Australia, Egypt, Albania, Argentina, Uruguay, Panama, Qatar, the Bahamas, Bahrain, Bermuda, British Virgin Islands, Turks and Caicos Islands, Suriname, Saint Lucia and Bolivia, Reuters reported.
The level 4 rating now has more than 100 countries as nations struggle to combat the highly contagious omicron variant.
The CDC advises that level 4 countries be avoided at all cost and a person be fully vaccinated if they do have to go to them.
Less than 20 countries are on the CDC's lowest warning level, level 1.
In the past few weeks, popular travel destinations for Americans such as Canada and Aruba have moved up to the highest warning due to increased COVID-19 cases.
Many countries paused travel from several African countries after the omicron variant was discovered to slow the spread of the virus, but the coronavirus still spread rapidly around the world.