The Rev. Jesse Jackson and his wife, Jacqueline, were being treated at a Chicago hospital Saturday after they were diagnosed with Covid-19, their representatives said in a statement.
The Rainbow Push Coalition, a civil rights organization founded by Jesse Jackson, 79, did not say why he and Jacqueline Jackson, 77, had to be hospitalized.
"Doctors are currently monitoring the condition of both," the organization said. "Anyone who has been around either of them for the last five or six days should follow the CDC guidelines."
The two were being treated at Northwestern Memorial Hospital.
Jackson got the Pfizer/BioNTech Covid-19 vaccine in January and used the occasion to encourage Black people to get vaccinated.
Although the coronavirus vaccines can prevent transmission and hospitalization, the virulent delta variant has been the source of a small proportion of "breakthrough" cases that can affect older and immunocompromised people.
Jackson announced in 2017 that he had Parkinson's disease.
Well-wishers Saturday included Bernice King, daughter of Jackson mentor Martin Luther King Jr., and Rep. Joaquin Castro, D-Texas.
Jackson ran for president unsuccessfully in 1984 and 1988. Some historians credit the campaigns with having set the stage for the election of President Barack Obama.