A critically ill Pope Francis, who is battling pneumonia in both lungs, “rested well,” the Vatican said Tuesday after earlier reporting a “slight improvement” in the condition of the 88-year-old head of the Roman Catholic church.

The Argentine pontiff was admitted to Rome’s Gemelli hospital on 14 February with breathing difficulties and bronchitis but his condition subsequently worsened and the Catholic faithful around the world have been praying for his recovery.

“The Pope rested well, all night long,” said the Vatican in a morning update on the 12th day of the Pope’s hospitalization.

The Holy See issued a more hopeful update Monday evening, saying the Pope’s “critical clinical conditions... demonstrate a slight improvement.”

It said Francis had experienced no more respiratory attacks — as he had suffered on Saturday, which required “high flow oxygen” — and some lab tests had improved.

But the Pope remains “a fragile patient,” as his doctor Luigi Carbone said Friday, and his medical team cautioned that it would take time for his drug treatments to show a positive effect.

“Considering the complexity of the clinical picture,” his doctors have declined to “decide on the prognosis,” the Vatican said Monday.

Francis, who is staying in a special papal suite on the 10th floor of the hospital, has continued to do some work and has moved from his bed to an armchair, while receiving the Eucharist in the morning.

Amid global concern over the Pope’s health, the Vatican said in its evening bulletin that “the critical clinical conditions of the Holy Father demonstrate a slight improvement.”

“Today there were no episodes of asthmatic respiratory attacks; some laboratory tests have improved,” it said, noting that Francis had worked in the afternoon after receiving the Eucharist in the morning.

On Monday evening, a few hundred faithful joined dozens of cardinals assembled in St. Peter’s Square to recite the rosary. The prayers for Francis — the leader of the Catholic Church since 2013 — was led by the Vatican’s secretary of state, Cardinal Pietro Parolin.

Oxygen that had been administered in recent days was given Monday “with slightly reduced flows and percentage of oxygen,” the Vatican said.

Francis’s medical team last Friday said he would remain in hospital for this entire week, at the very least.

The Vatican has been issuing twice-daily updates on the Pope, and earlier Monday said he spent a peaceful night. A Vatican source added that he was “not in pain,” was eating “normally,” and was even “in a good mood.”

In the evening the Pope called the parish priest of Gaza, the Vatican said.

The longest hospitalization of Francis’s near 12-year papacy has brought an outpouring of support for the pontiff, with prayers said around the world and tributes left outside the hospital.