Scientists used a mouse model to compare tissue after infections had cleared. They examined lungs and brains to see which effects were common to severe respiratory infections and which were specific to COVID-19. The study compared outcomes after COVID-19 and after influenza.
Both viruses left signs of lasting lung injury. Immune cells did not fully stand down and more collagen built up, which can cause scarring and stiffer lungs. This may explain lingering shortness of breath. After influenza, specialized repair cells appeared and began to rebuild the airway lining, but that repair response was largely missing after COVID-19. COVID-19 also caused persistent brain inflammation and tiny areas of bleeding in some mice, changes that were mostly absent after influenza.
Difficult words
- tissue — parts of the body like skin or organs
- collagen — protein that gives structure to tissues
- scarring — hard marks left after body heals
- inflammation — body reaction with redness and swelling
- persistent — continuing for a long time
- immune — relating to the body's disease protection
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- How could scarring and stiffer lungs change a person's breathing?
- Why is it important that repair cells rebuild the airway lining after an infection?
- How would you feel if you had lingering shortness of breath after an illness?
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