After daily audiences he was taken to Rome’s Gemelli Polyclinic, the Vatican said in a short statement on Friday morning.
“Pope Francis will be admitted to the Agostino Gemelli Polyclinic for necessary diagnostic tests and to continue hospital treatment for his ongoing bronchitis,” it said.
It later added: “The Holy Father… has undergone specialist examinations and has started hospital drug therapy.”
“The initial tests showed a respiratory tract infection,” the Vatican said. “His clinical condition is fair; he has a slight fever.”
It is still not clear how long the Pope will stay in hospital.
His public meetings have been cancelled until at least Monday.
The 88-year-old leader of the Catholic Church was diagnosed with bronchitis last Thursday, but since then has continued his activities and audiences.
However, during his last two Wednesday general audiences at the Vatican, Pope Francis asked an aide to read his prepared remarks.
“Me, with my bronchitis, I cannot (read) still,” the Pope said on Wednesday. “I hope that next time I can.”
Before going to hospital on Friday, the Pope met with Slovak Prime Minister Robert Fico and the head of CNN Mark Thompson.
Francis had part of one lung removed as a young man and has long battled health problems – including long bouts of bronchitis in the winter.
He uses a wheelchair, walker or cane when moving around and recently fell twice, hurting his arm and chin.
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Rome’s Gemelli hospital, the largest in the city, has a special suite for treating popes.
Francis spent nine days there in June 2023, when he had surgery to repair an abdominal hernia.
