Pope Francis, who is in critical condition in hospital battling double pneumonia, rested well throughout the night, the Vatican said on Tuesday. The 88-year-old pope was admitted to Rome's Gemelli hospital on February 14 with a serious respiratory illness that has since triggered other health problems.

The eyes of the Catholic world are focused on Agostino Gemelli Hospital in Rome, where Pope Francis remains hospitalized for a number of health issues. Here's what to know about the Pope's health situation—and what experts think it says about the risks of respiratory infections in older people.