Pope Francis, 88, who has been in hospital since February 14 with pneumonia in both lungs, has been gradually improving and talk has turned to when he might go home.

But the Argentine has still not been seen in public since his admission, and in an audio message released on March 6, the octogenarian sounded weak and breathless.

Here is what we know about the health of Francis, who will mark on Thursday 12 years as head of the Catholic Church and its almost 1.4 billion followers.

Respiratory attacks

Francis suffered several respiratory attacks during his stay at Rome's Gemelli hospital, which raised concerns for his life.

On February 22 the Vatican said he had that day suffered a "prolonged asthmatic respiratory crisis", and also required blood transfusions for thrombocytopenia, a condition that can prevent clotting and lead to continued bleeding.

On February 28 the pope suffered "an isolated crisis of bronchospasm" - a tightening of the muscles that line the airways in the lungs - which caused "an episode of vomiting with inhalation", the Holy See said.

On March 3 Francis suffered "two episodes of acute respiratory failure" and doctors performed two bronchoscopies in order to remove "abundant secretions".

After that, the Vatican said he was wearing an oxygen mask at night, switching during the day to high-flow oxygen delivered through a cannula, a plastic tube tucked into the nostrils.

Improvements, talk turns to home

Since March 4, the Vatican has reported gradual improvements in the pope's condition, and on March 10 announced in a medical bulletin that it was changing his prognosis, which for weeks had been "reserved", meaning uncertain.

"The improvements recorded in the previous days have been further consolidated, as confirmed by blood tests and clinical objectivity and the good response to pharmacological therapy," it said.

A Vatican source said he still had pneumonia but confirmed "there is no imminent danger" to his life.

The Vatican bulletin also raised for the first time the prospect of an end to Francis's hospitalisation, talking of "days" of treatment ahead.

"Given the complexity of the pope’s clinical picture and the severe infection present at the time of hospitalisation, it will still be necessary to continue pharmacological treatment in a hospital setting for several more days," it said.

On March 11, the Vatican press office gave a briefing saying the pope remained stable, with "slight improvements within a framework for doctors that remains complex".

It refused to speculate on when Francis might go home.

Regular updates

The pope has been staying in a special suite on the 10th floor of the hospital, alternating prayers with physiotherapy, as well as doing some work and receiving colleagues, the Vatican says.

He has in recent days also joined via video link - without being seen - spiritual exercises (prayers and meditations) held at the Vatican.

In a notable shift towards transparency compared to previous papacies, the Vatican has been providing daily updates, at the request of Francis himself.

The morning statement, issued shortly after 0700 GMT, is normally one line describing his night's sleep, followed by a more detailed medical bulletin at around 1800 GMT. 

Since March 7, due to the stability of his condition, the Vatican has only issued the evening bulletin every other day. The next is due on Wednesday evening.

The Vatican press office also provides regular updates.

However, Francis has not been seen in public since being hospitalised, notably missing four successive Sunday Angelus prayers, and no photos have been released.

In the audio message, in which Francis thanked well-wishers for their prayers, the pope sounded very frail.

Longest hospital stay

This is the longest and most fraught hospital stay since Francis became pope on March 13, 2013.

But he has had health issues for years, even while maintaining a packed schedule, including frequent overseas visits.

Francis was treated at the Gemelli between July 4 and July 14, 2021, for surgery for diverticulitis, an inflammation of pockets that develop in the lining of the intestine.

In March 2023, he was an inpatient for three days for bronchitis and between June 7 and June 16 that year was admitted for a hernia operation.

As a young man, he had part of his right lung removed, making him more susceptible to respiratory infections.

Knee and hip pain have forced him to use a wheelchair since 2022. He underwent cataract surgery in 2019 and recently began wearing a hearing aid.