Rome. Pope Francis participated remotely in the Vatican’s spiritual retreat Tuesday after receiving encouraging news from his doctors: They upgraded his prognosis, saying he is no longer in imminent danger of death from the respiratory infection that has kept him hospitalized for nearly a month—his longest and most serious health crisis in his 12-year papacy.

The 88-year-old pope is not fully recovered yet. Doctors remain cautious and have decided to keep him hospitalized for several more days for treatment and rehabilitation.

Dr. Carmelo D'Asero, an infectious disease specialist and expert in geriatric illnesses, said Francis was making slow but steady progress. However, he noted that it remains unclear when the pope can return to the Vatican or whether he will require supplemental oxygen long-term.

“We must not forget that he has been hospitalized for a month,” said D'Asero, who is not involved in Francis' care. He added that the arrival of spring in Rome should help, as Francis’ bronchitis typically worsens during the winter months.

“We are entering a warm season, which is certainly beneficial for those with respiratory diseases,” he said. “I think he will return to work, but with a lighter schedule and continuous oxygen therapy monitoring.”

Francis, who has chronic lung disease, continues to use supplemental oxygen during the day and a ventilation mask at night.

The Vatican said Francis resumed physical and respiratory therapy Tuesday and followed the Vatican's weeklong spiritual retreat via videoconference for a third consecutive day.

"It really makes me happy because we were sad when it seemed like he wasn’t recovering," said Sister Maria Letizia Salazar, a nun who prayed for Francis on Tuesday outside Gemelli Hospital. "But now that I’ve heard this news, I am very happy."

This week also marks significant anniversaries for Francis: Tuesday was the 67th anniversary of his entry into the Jesuit religious order, and Thursday will be the 12th anniversary of his election as pope.