VATICAN CITY — A hard-headed hospital nun who disobeyed a doctor’s orders saved the life of Pope Francis some six decades ago when he risked dying of pneumonia, the Pope reveals in a new book.

When Francis was studying for the priesthood in Latin America in the 1950s he caught pneumonia, but it was misdiagnosed by the seminary’s doctor, who thought is was the flu, and one day had to be rushed to the hospital “on the point of death,” he says.

A doctor at the hospital realized it was pneumonia and ordered staff to give the young Jorge Mario Bergoglio two types of antibiotics.

But a hospital nun named Cornelia Caraglio, had a different idea.

“As soon as the doctor left (she told the staff) ‘let’s double the dose.’ She certainly was a wise nun. By ordering that the dose be doubled she saved my life,” he said.

Several months later, the future Pope returned to the hospital to have the upper part of one of his lungs removed because of an infection.

Francis, 81, made the comments in a book-length interview with Spanish priest Fernando Prado called “The Strength of Vocation,” in which he discusses the challenges of being a priest or nun today.

It is due to be published this week in several languages. An advance copy of the Italian version was made available to Reuters.