On August 6, in close coordination with the U.S. Centers for Disease Control and Prevention (CDC), the Department of State lifted the Global Level 4 Health Advisory. The Global Advisory, initially put in place on March 19, 2020, advised U.S. citizens to avoid all international travel due to the global impact of COVID-19. The US State Department is returning to the previous system of country-specific levels of travel advice (with Levels from 1-4 depending on country-specific conditions).
US citizens are being advised to review the entire Travel Advisory for their travel destinations on Travel.State.gov before travelling. You can find the UK's page at https://travel.state.gov/content/travel/en/traveladvisories/traveladvis….