ROME >> Doctors on Saturday prescribed “absolute rest” for Pope Francis and modified the treatment for his respiratory tract infection, the Vatican said, a day after the 88-year-old pope was admitted to a hospital following a weeklong bout of bronchitis.

On doctors’ orders, Francis won’t deliver his traditional Sunday noon blessing, which he could have done from his hospital room if he was well enough.

The Argentine pope, a known workaholic who keeps up a grueling pace despite his many ailments, was admitted to Rome’s Gemelli hospital on Friday after his bronchitis worsened. It was his fourth hospitalization since his 2013 election and raised questions about his increasingly precarious health.

Preliminary tests showed that he had a respiratory tract infection, which was confirmed Saturday. In a late afternoon bulletin, the Vatican said that Francis had no fever on Saturday and that tests showed improvement in some parameters.

Francis slept well during a quiet first night in the hospital, ate breakfast, read the newspapers and received the Eucharist on Saturday, alternating rest with prayer and reading during the afternoon, the Vatican said.

The Vatican canceled his audiences through Monday at least.

Francis, who had part of one lung removed after a lung infection when he was a young man, has kept up a frenetic pace of late. He has packed his days with private audiences while taking on the added obligations of steering the Catholic Church through its Holy Year.

Starting at Christmas, he has had Jubilee events nearly every other weekend, including one honoring the armed forces last weekend in which he presided over a chilly outdoor Mass, despite having already been diagnosed with bronchitis, and advice to stay indoors.

On Monday alone, he met separately with the Vatican ambassador to Croatia, a group of visiting bishops from Madagascar, the European Union’s foreign policy chief, a candidate to be the next UNESCO chief, the rector of the grand mosque of Paris and Nikas Safronov, a Russian painter.

This weekend, he was supposed to have presided over a Jubilee audience for artists, celebrate Mass for them and then on Monday, meet with them at Rome’s famed Cinecitta film studios. Instead, they and thousands of other pilgrims gathered and prayed for the pope in a basilica on Saturday morning.

“Pope Francis is always pushing himself, he always wants to fulfil his commitments at all costs,” said the Rev. Enzo Fortunato, communications director for St. Peter’s Basilica. “And then not to make the situation worse ‘Holy Father that’s enough now.’ And he obeyed, he obeyed.”

Francis, who is prone to respiratory infections in winter, was diagnosed with bronchitis on Feb. 6, but had continued to hold daily audiences in his Vatican hotel suite. But he handed off his speeches for an aide to read aloud, saying he was having trouble breathing.