Three US senators from different political affiliations and different parts of the country said Thursday they have tested positive for the coronavirus.

The lawmakers, who were vaccinated, are among the 71 members of Congress to be diagnosed with Covid-19 since the beginning of last year, according to the nonpartisan group GovTrack.

"I've tested positive for a breakthrough case of COVID-19. I feel good but will isolate per docs instructions," Senator John Hickenlooper, 69, said on Twitter.

"I'm grateful for the vaccine," the Colorado Democrat added, as he encouraged other people to get the shot. 

Republican Senator Roger Wicker, 70, tested positive earlier Thursday "after immediately seeking a test due to mild symptoms," his office said in a statement. 

Wicker is being treated by a doctor in Mississippi, his home southern state with the 10th highest infection rate in the nation.

A third senator, 77-year-old Angus King, was tested Thursday as a precaution after he began experiencing symptoms.

"While I am not feeling great, I'm definitely feeling much better than I would have without the vaccine," said King, an independent from Maine where the Covid infection rate is relatively low.

Congress is currently on recess, and the Senate comes back into session September 13.

Last February 67-year-old House Republican Ron Wright, who lived for years with cancer, died two weeks after contracting Covid-19.