The advisories warn against travel by unvaccinated travelers unless their trips are necessary.
The government has maintained a strict observance of the pandemic situation across the globe, adding new nations to the list as their numbers climb in the face of the delta variant.
Health officials added Israel, Thailand, French Polynesia and several other countries to its list of "Level 4: Very High" risk travel destinations. At the same time, the U.S. State Department issued a Level 4: "Do Not Travel" advisory for Iceland and France.
"If you must travel to these destinations, make sure you are fully vaccinated before travel," the CDC warning states.
The list of Level 4 destinations includes 73 countries, such as Brazil, the United Kingdom, Ireland, Costa Rica, Saudi Arabia and others.
The list of Level 3: "High" risk nations is almost twice as long and includes many popular travel destinations, including Jamaica, Italy, Croatia, Barbados, the Bahamas and more.