Pope Francis remains in critical condition as he continues treatment for pneumonia and a complex lung infection, the Vatican said Sunday. Medical tests have revealed mild signs of kidney failure, adding to concerns about the 88-year-old pontiff's health as he remains hospitalized at Rome's Gemelli Hospital.

"The complexity of the clinical picture, and the necessary wait for pharmacological therapies to provide some feedback, require that the prognosis remain reserved," the Vatican said in a statement. Doctors are closely monitoring the pope's condition, noting that while his kidney function is under control, he continues to require high levels of supplemental oxygen.

Despite his deteriorating health, the Vatican said Francis remained "vigilant and well-oriented" and took part in a private Mass from his hospital apartment on Sunday morning. The service was attended by members of his medical team and staff.

The pope's hospitalization has now entered its second week after he was admitted on February 14 with respiratory issues initially thought to be related to bronchitis. A later CT scan confirmed pneumonia in both lungs. Although Francis has not experienced further respiratory crises since Saturday night, doctors have expressed concern over the potential development of sepsis, a serious bloodstream infection that can arise as a complication of pneumonia.

Dr. Jamin Brahmbhatt, a urologist at Orlando Health Medical Group, told CNN that while mild kidney failure is not uncommon in elderly patients battling severe infections, the risk of complications remains. "Infections can quickly worsen if the body's immune response kicks into overdrive-something we call sepsis," he said. "When pneumonia leads to sepsis, widespread inflammation can hurt multiple organs, including the kidneys."

The Vatican's latest update comes as global prayers for Francis continue to pour in. In New York, Cardinal Timothy Dolan acknowledged the gravity of the situation, describing the Catholic faithful as being "at the bedside of a dying father." He later told reporters he remained hopeful that Francis would recover.

In Argentina, Catholics gathered at Buenos Aires Cathedral to pray for the pope's health. The city's iconic obelisk was lit with the message, "Francis, the city prays for you." Across Italy, bishops led special rosary prayers and held Masses dedicated to his recovery.

On Sunday, the Vatican's Holy Year celebrations proceeded without Francis, marking the second consecutive week that the pope has been unable to deliver his weekly Angelus prayer. Archbishop Rino Fisichella, organizer of the Holy Year events, celebrated Mass in St. Peter's Basilica on Francis' behalf, telling the congregation, "Even though he is in a hospital bed, we feel Pope Francis close to us."

Francis, who had part of his lung removed as a young man due to a severe bout of pneumonia, has struggled with respiratory issues throughout his life. In 2021, he underwent surgery to remove part of his colon due to diverticulitis. Last year, he was hospitalized for bronchitis, and in recent months, he suffered two falls that left him with injuries requiring a sling.

Medical professionals have emphasized that Francis' primary health risk remains sepsis. On Saturday, doctors administered blood transfusions to address low platelet levels and anemia, which could indicate his body is struggling to combat infection. The pope was also given hematin, a treatment designed to increase hemoglobin levels and improve oxygen circulation.

While Vatican officials have dismissed speculation that Francis could resign due to his condition, his recent decisions suggest he has been preparing for a transition in leadership. Last year, he revised funeral rites for popes, simplifying the ceremonies while maintaining key traditions for papal succession. In December, he elevated 21 new cardinals, ensuring a significant number of electors would be aligned with his vision for the Church.

Earlier this month, before his hospitalization, Francis extended the terms of Cardinal Giovanni Battista Re, the 91-year-old dean of the College of Cardinals, and Cardinal Leonardo Sandri, his 81-year-old vice-dean. Their roles are central in the event of a papal conclave.