VATICAN CITY — Pope Francis, in a stable condition as he battles pneumonia in hospital for the 17th day, met two Vatican officials on Sunday and offered thanks to well-wishers for their prayers and support in a written message.

Francis, 88, was admitted to Rome’s Gemelli hospital on February 14 with respiratory problems that degenerated into double pneumonia — a serious infection in both lungs that can inflame and scar them, making it difficult to breathe.

The Vatican said on…