If you, being a sensible person, refuse to get the covid shot but have been dreaming of visiting a foreign country that does NOT require said shot, you WILL be required to get one upon your return. Yep. And you thought this was a free country. Sorry, no such luck.

See U.S. State Department FAQ.

"Starting on December 6, before boarding a flight to the United States, air travelers aged two and older, regardless of nationality or vaccination status, are required to show documentation of a negative viral test result taken within one day of the flight's departure. You must show your negative result to the airline before you board your flight. That includes all travelers " U.S. citizens, lawful permanent residents (LPRs), and foreign nationals."