Pope Francis was in critical condition Saturday after he suffered a prolonged asthmatic respiratory crisis while being treated for pneumonia and a complex lung infection, the Vatican said. The 88-year-old pope,

More clinical tests were being performed on the 88-year-old pope, who had part of one lung removed as a young man.

In light of Pope Francis’ latest diagnosis, Dr. Leana Wen explains why older adults are especially at risk for serious disease due to respiratory infections.