Pope Francis returned to work on Saturday morning after being struck down by a fever which interrupted his regular schedule and sparked renewed concerns for his health.

Francis canceled all of his meetings on Friday morning due to the illness. However, the daily appointment schedule sent by the Vatican Saturday showed that Francis was resuming his work.

The Vatican did not issue any new update on the 86-year-old pontiff's health.

Francis is expected to celebrate mass for Pentecost in St. Peter's Square on Sunday.

On Thursday, the Vatican Secretary of State, Cardinal Pietro Parolin, said Francis was "tired" after a "very intense day," according to Italian news agency ANSA.

"The Pope was tired. Yesterday he had a very intense day and saw many people. There was the meeting with Scholas Occurrentes and he wanted to greet each person individually. At a certain point, one becomes less resistant," Parolin said.

Francis was seen looking well Thursday afternoon at a live-streamed event from the Vatican for Scholas Occurrentes, an international education network that he founded, according to CNN's team on the ground.

He was hospitalized in March for bronchitis but responded well to antibiotics.

Leaving hospital on that occasion, the Pope joked that he's "still alive."

The pontiff -- who as a young man suffered from severe pneumonia and had part of a lung removed -- has had a recent history of medical issues.

He has often been seen with a walking stick and sometimes uses a wheelchair due to pain in his right knee.

Last year, he canceled a trip to the Democratic Republic of Congo (DRC) and South Sudan after doctors said he might also have to miss a later trip to Canada unless he agreed to have 20 more days of therapy and rest for his knee. He ultimately went to the DRC and South Sudan in February.

Francis also suffers from diverticular disease, a common condition that can cause the inflammation or infection of the colon. In 2021, he had surgery to remove part of his colon.