Pope Francis is still critically ill as he battles double pneumonia, but his condition has shown a "slight improvement", the Vatican said on Monday.

Time-honored rituals, drafted and refined over centuries, allow for ritual mourning and provide order at a dramatic moment of transition.

Francis was also given blood transfusions, according to the Vatican, after blood tests revealed he was suffering from thrombocytopenia, meaning the platelet count in his blood was too low, a condition the doctors said is associated with anemia. Infections and medical treatment may lower platelet count.