The pope's infection will require further hospitalization, the Vatican said Monday, as concerns grew about the increasingly frail 88-year-old pontiff.

The Vatican said Monday that Pope Francis’ respiratory tract infection is presenting a “complex clinical picture” that will require further hospitalization.

Pope Francis was hospitalized Friday after a weeklong bout of bronchitis worsened and was receiving drug therapy for a respiratory tract infection, the Vatican said. It was the latest setback to the 88-year-old's pontiff's health that forced him to cancel his agenda through Monday at least.

Pope Francis was hospitalized Friday with a mild fever and a respiratory tract infection, according to the Vatican. His health has forced him to cancel his scheduled events through Monday. Vatican spokesman Matteo Bruni said that the pope is in "good spirits" amid the health issues,

The Vatican says Pope Francis’ respiratory tract infection is presenting a “complex clinical picture” that will require further hospitalization

Francis was serene after arriving at Rome’s Gemelli hospital after presiding over his morning audiences, Vatican spokesperson Matteo Bruni said.

The Argentine pope, a known workaholic who keeps up a grueling pace despite his many ailments, was admitted to Rome’s Gemelli hospital on Friday after a weeklong bout of bronchitis worsened. It was his fourth hospitalization since his 2013 election and raised questions about his increasingly precarious health.

The first tests carried out on Pope Francis have revealed he has a respiratory tract infection, the Vatican press office said on Friday. The pontiff decided to go to Rome's Gemelli hospital for treatment and tests after suffering bronchitis and breathing problems,