The US Department of State this week added the UK, Canada, France, Israel, Mexico, Germany and 110 other countries to its "Level Four: Do Not Travel" advisory list, bringing the total to 150 countries, because of a "very high level" of COVID-19.
According to a State spokesperson, these wholesale additions to the Level 4 list reflect an increased reliance on US CDC "existing epidemiological assessments" of subject countries, and ultimately about 80% of countries worldwide could be placed at Level 4.
The State Department advisories are not mandatory, and do not per se bar Americans from traveling.