Following a respiratory tract infection, Pope Francis was diagnosed with double pneumonia. According to the BBC, the pontiff is particularly susceptible to pneumonia and is currently in a critical posiiton.

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.

The kidney ailment appears to be in an early stage, the Vatican said, adding that the pontiff is still receiving high flows of oxygen for his respiratory illness.