POPE FRANCIS HAS shown “a truly surprising improvement” since returning to the Vatican to convalesce after surviving a life-threatening bout with double-pneumonia, the doctor who coordinated the pontiff’s five-week hospital stay said.

“I find him very lively,” Dr Sergio Alfieri said after visiting the pope at his apartment in the Santa Marta Domus on Wednesday, three days after his release from Rome’s Gemelli hospital.

“I believe that he will return if not to 100%, 90% of where he was before.”

Francis appeared frail and weak as he greeted a crowd of well-wishers from a hospital balcony on Sunday.

His voice was waning as he praised a woman in the crowd for bringing yellow flowers.

Pilgrims pictured in St. Peter's Square on Wednesday. Alamy Stock Photo Alamy Stock Photo

He was able to only partially lift his arm to bless the people and he gasped for air as he was wheeled back inside.

Alfieri said the pope’s voice was regaining strength, and that his reliance on supplemental oxygen has decreased.

The limited mobility of his arm was due to an unspecified trauma he sustained before being taken to hospital, and that will take time to heal, Alfieri said.

The 88-year-old pope was taken to hospital on February 14 after a long bout with bronchitis that left him breathless at times, and which quickly developed into double pneumonia and revealed a polymicrobial (viral, bacterial and fungal) respiratory infection.

Throughout the ordeal, doctors emphasised the complexity of his condition, given his age, lack of mobility requiring a wheelchair, and the removal of part of a lung as a young man.

Alfieri repeated that he did not think the pope would make it after a severe respiratory crisis a week after being taken to hospital, and he informed the pope that a “decisive” treatment necessary to save him would put his organs at risk.

The doctor preferred to describe the treatment as “decisive”, and not aggressive, and emphasised that no extraordinary, life-extending measures were ever taken.

The incident was one of several critical moments when the pope’s life hung in the balance, Alfieri said.

While Francis beat the double pneumonia in the hospital, he is continuing to receive treat the fungal infection, which is expected to take months to resolve.

The pope is also receiving physical, respiratory and speech therapy. Doctors have ordered him to rest for at least two months and to avoid crowds.