Long COVID-19 has been described as the “pandemic after the pandemic,” with around 1 in 5 adults experiencing chronic symptoms after an infection – numbering to tens of millions suffering respiratory, cognitive and neurological impairments that can affect their daily life.

Researchers are still learning why the condition develops. Some, like immunologist Harish Narasimhan and his colleagues in the Sun Lab at the University of Virginia, point to the potential role of the immune system itself.

Narasimhan and his team conducted a review on what’s currently known about chronic symptoms that persist after viral respiratory infections like COVID-19, the flu and the common cold. They found that while a strong immune response may be indispensable to flushing out an invading virus, an overactive immune system that rages on in the lungs long after the fight is over can lead to more damage than good.

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Vivian Lam

Assistant Health and Biomedicine Editor

The immune system usually stays dormant in the lungs in times of health. wildpixel/iStock via Getty Images

Long COVID-19 and other chronic respiratory conditions after viral infections may stem from an overactive immune response in the lungs

Harish Narasimhan, University of Virginia

While a strong immune response is essential to fight against viral infection, an immune system that continues to stay active long after the virus has been cleared can lead to lung damage.

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