Pope Francis celebrates the Holy mass of the Epiphany in St Peter's Basilica at the Vatican on January 6, 2025. Andreas Solaro, AFP

VATICAN CITY, Holy See (2nd UPDATE) -- Pope Francis's condition showed "a further, slight improvement", the Vatican said Wednesday, while continuing to maintain the prognosis for the 88-year-old fighting pneumonia in both lungs was "reserved."

"The clinical conditions of the Holy Father in the last 24 hours have shown a further, slight improvement," said the Vatican in its nightly bulletin on the health of the pontiff, who has been in hospital since February 14.

"Although a slight improvement is being recorded, the prognosis remains reserved," it said.

The Argentine pope was originally admitted to Rome's Gemelli hospital with breathing difficulties and bronchitis, but his condition subsequently deteriorated, sparking widespread concern among Catholics.

Respiratory attacks he suffered at the weekend that required high levels of oxygen and blood transfusions have not repeated, according to the Vatican, although he continues to receive oxygen and do breathing exercises.

READ: Critically-ill pope out of bed, resting -- Vatican source

On Wednesday, the Vatican said a CT scan performed Tuesday showed "normal progression of the pulmonary inflammatory condition" while blood tests on Wednesday confirmed the improvement.

It also said that a mild renal insufficiency detected at the weekend "had resolved."

As Catholics across the globe pray for Francis, doctors have warned the path to recovery could be long, with the Jesuit pontiff likely staying in hospital beyond this week.

Despite his critical condition, the leader of the world's nearly 1.4 billion Catholics has kept up with Church matters from his hospital suite, according to the Vatican.

Now on his 13th day in the hospital, the pope Wednesday was "sitting in a chair, and continuing with the treatment as normal", a Vatican source said.

The Vatican said he received the Eucharist in the morning and spent his afternoon working.

The current hospitalization is Francis's fourth and longest.

The pope, who had part of one of his lungs removed as a young man, has suffered increasing health problems in recent years.

He is prone to bronchitis and suffers from hip and knee pain, which has made him reliant on a wheelchair.

Pilgrims and faithful have been flocking to the Vatican and the Gemelli to pray for Francis, with a fresh round of prayers held in St Peter's Square later Wednesday evening.

© Agence France-Presse

RELATED VIDEOS: