In a late update on Sunday, the Vatican said Pope Francis hadn't had any more respiratory crises since Saturday night but was still receiving high flows of supplemental oxygen

Some blood tests showed "initial, mild, kidney failure," but doctors said it was under control

"The complexity of the clinical picture, and the necessary wait for drug therapies to provide some feedback, dictate that the prognosis remains guarded," Pope Francis' doctors concluded

Prayers for Francis, meanwhile, poured in from around the world, from his native Argentina to the seat of Sunni Islam in Cairo to schoolchildren in Rome

Pope Francis was supposed to celebrate Mass on Sunday morning in St Peter's Basilica and ordain deacons as part of the Vatican's yearlong Holy Year commemoration

The organizer of the Holy Year, Archbishop Rino Fisichella, celebrated the Mass in his place and offered a special prayer for Francis from the altar before delivering the homily the pope had prepared

"Even though he is in a hospital bed, we feel Pope Francis close to us. We feel him present among us," Fisichella told the hundreds of white-robed deacons

A prewritten message that had been prepared for Francis to read Sunday, but he did not deliver, said he was "confidently continuing my hospitalization at the Gemelli Hospital, carrying on with the necessary treatment; and rest is also part of the therapy!" The message asked for prayers for him, as he always asks, and noted the upcoming anniversary of Russia's invasion of Ukraine, "a painful and shameful occasion for the whole of humanity"

Meanwhile in Francis' native Argentina, Catholics prayed for the pope at the Buenos Aires cathedral and the city's iconic obelisk was lit up "Francis, the city prays for you"