People with lung diseases like emphysema or bronchitis have lungs that are weaker when trying to fight off the respiratory infection.
When COVID-19 — the disease caused by the new coronavirus — travels through the body, it can attack the lungs.
The infection causes inflammation in the lungs' lining; irritation in the nerves around them; and can cause inflammation in the air sacs at the bottom of lungs. That can lead to pneumonia — when the lungs fill up with fluid.
Inflamed air sacs also mean that lungs are unable to get enough oxygen into the bloodstream or remove the byproduct carbon dioxide, The Guardian reported, citing respiratory physician John Wilson. It can cause vital organ failure, and can be fatal.