Pope Francis says he is indebted to a nun who saved his life at age 21 when he was suffering from a lung infection, according to a new book written by Vatican journalist Andrea Tornielli.

The Telegraph reported Sunday that the pope related to Tornielli in "The Little Flowers of Pope Francis" how he was taken care of by nuns during his illness.

"I am alive thanks to one of them," Pope Francis said. "When I had lung problems in the hospital, the doctor gave me penicillin and antibiotics in small doses.

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"The nun who was on the ward tripled that because she had an intuition, she knew what to do, because she was with the ill all day long," he added.

There were concerns about the pope's health when he was chosen by the cardinals in March, after it was revealed that he had a lung removed when he was a teenager. The concerns were heightened by the fact that his predecessor, Pope Benedict VXI, cited health problems as the main reason for stepping down as head of the Catholic Church.

"His health is good and he shows great stamina," Tornielli told The Telegraph. "He works many hours a day and spends many hours a week greeting people in St. Peter's Square in the freezing cold."

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