Pope Francis , in critical condition battling double pneumonia, rested well all night, the Vatican said on Tuesday.
The pope was admitted to Rome's Gemelli hospital on February 14 with a serious respiratory illness that has since triggered other health problems.
The 88-year-old pontiff spent his 11th night in Rome's Gemelli Hospital, making it the longest hospital stay of his nearly 12-year papacy.
"The clinical conditions of the Holy Father, in their critical nature, show a slight improvement," the health update read.
The pope, it said, was still receiving oxygen, "although with slightly reduced flow and oxygen percentage".
It added that the "mild kidney insufficiency," which was first reported on Sunday, was "not a cause for concern".
A Vatican official, who did not wish to be named because he was not authorised to speak about the pope's condition, earlier said that Francis was eating normally and was able to get up and move about his hospital room.
Monday's statement said the pope had resumed work in the afternoon and in the evening made a call to the Catholic parish in Gaza, which the pope has done frequently during the Israel-Hamas war.
On Sunday, the Vatican described the pope's condition as critical for a second day in a row.
On Saturday, it said the pope had needed a blood transfusion after experiencing a "prolonged asthma-like respiratory crisis".
Monday's update said the pope had not had further respiratory crises and that some of his laboratory tests "have improved".
Double pneumonia is a serious infection that can inflame and scar both lungs, making it difficult to breathe. The Vatican has described the pope's infection as "complex," and said it was caused by two or more microorganisms.
The pope's prolonged illness has provoked an unusual amount of public speculation among cardinals, the highest officials in the 1.4 billion-member Catholic Church after the pontiff.
New York Cardinal Timothy Dolan, who is not known as close to Francis and did not cite information beyond the Vatican's medical updates, said in a homily during Mass at his cathedral on Sunday that the pope was "probably close to death".
German Cardinal Gerhard Muller, a former Vatican official known to have disagreed with Francis on doctrinal issues, admonished prelates who were publicly speculating about the pope's condition or planning for a conclave, the secret gathering of cardinals to elect a new pope.
He told Italy's Corriere della Sera that cardinals were not receiving any more information than the public about the pope's condition.
"The pope is still alive and this is a moment for prayer," he said. "If there is anyone who is looking to the future while Francis is in the hospital, that's good for nothing."
Cardinal Pietro Parolin, the Vatican's number-two official, led a prayer service for Francis in St Peter's Square on Monday evening attended by pilgrims and senior Church figures. The service is set to be repeated daily.
Parolin prayed that the Virgin Mary would "sustain (Francis) in this moment of sickness and trial, and help him recover his health soon".
Outside Gemelli Hospital, groups also gathered to pray for Francis near a statue of the late Pope John Paul II, who was treated at the facility many times over his 1978-2005 papacy.
Maria Vozlv, a Ukrainian who has lived in Rome for 18 years, said many in her home country were concerned.
"We Ukrainians are really praying for him," Vozlv said. "He needs to get well and come home."
