Pope Francis’ respiratory tract infection is presenting a “complex clinical picture” that will require further hospitalization, the Vatican said Monday as concerns grew about the increasingly frail health of the 88-year-old pontiff.

The pope has been recovering at a Rome hospital for at least two nights. According to the Vatican, the pope is pulling back from some of his duties, including leading certain prayers.

Francis was first admitted to Rome’s Gemelli Hospital two weeks ago, after being plagued by a string of lung-related medical struggles, including bronchitis and then pneumonia.

The slight renal insufficiency the pope had in recent days subsided and a CAT scan of the chest showed a normal evolution of the pulmonary inflammatory picture.

The prognosis remains uncertain," the Vatican said Tuesday. The pope resumed his work activities after receiving the Eucharist. The pope "rested well, all night long," sleeping without interruption, Vatican sources told ABC News.

According to the one-line morning bulletin Friday, “The night went well, this morning Pope Francis got up and had breakfast.” Francis was admitted to Rome's Gemelli hospital on Feb. 14 after a case of bronchitis worsened;

On Wednesday, the Vatican said Pope Francis “had a tranquil night, woke up and had breakfast,” saying he was in good spirits. Here’s a look at what a pneumonia diagnosis can mean and potential treatments doctors might be trying: Pope Francis was admitted to Rome’s Gemilli hospital in “fair” condition on Friday after his bronchitis worsened.

Pope Francis remains hospitalized in Rome as doctors treat a worsening respiratory infection that the Vatican has described as a "complex clinical picture." The 88-year-old pontiff was admitted to Gemelli Hospital on Friday following a weeklong struggle with bronchitis that required additional medical intervention.

The 88-year-old pontiff was initially admitted to the hospital on Friday for bronchitis. On Monday, the Vatican said test results show Francis has "a polymicrobial infection of the respiratory tract."

Dem dey treat Pope Francis for one "tough clinical situation" and e go remain for hospital for as long as necessary, di Vatican tok. Dem admit di 88-year-old to Rome Gemelli hospital on Friday to undergo treatment and test for bronchitis.

On Monday, the Vatican said the pontiff has a "polymicrobial infection" of his respiratory tract, which has required a change in his treatment. A later update added that the Pope was "proceeding with the prescribed treatment" in a stable condition and did not have a fever.