The Vatican has detailed laws and rituals to ensure the transfer of power when a pope dies or resigns, but not when he is sick

Under Catholic canon law, the pope holds several key titles, including the successor of the Apostle Peter, the head of the college of bishops, the Vicar of Christ and the pastor of the universal Catholic Church. These roles, along with his power, have remained unchanged since he became the 266th pope on March 13, 2013.

As Pope Francis remains in critical condition at Gemelli Hospital in Rome - still in charge of the Vatican and the worldwide Roman Catholic church - millions of the devout are praying for his full recovery,