Covid’s Long-Term Effects on the Lungs, Gut, Brain and More

Five years — and hundreds of millions of cases — after the World Health Organization declared the Covid-19 pandemic, scientists are getting a clearer picture of how the virus can affect the body long after an infection seems to pass.

Some of Covid’s effects became apparent soon after the virus began spreading. We quickly understood how deadly an infection could be, especially for those with underlying conditions like diabetes and heart disease. But it has taken years of research to start making sense of how a bout of Covid can lead to lasting, sometimes invisible changes in different parts of the body.

Some of these effects, such as chronic fatigue and brain fog, are considered long Covid, defined as symptoms from an infection that persist for at least three months. By some estimates, 400 million people worldwide have been diagnosed with some form of long Covid. But an infection can also lead to other issues, including lung and heart damage and microbiome changes in the gut, that may not always be recognized as long Covid but can still have a lasting effect on our health.

We now have a better sense of what might be behind those changes, including the role of the widespread inflammation that Covid can cause. For most people, inflammation will subside once the virus clears. But for some, if it “rages” too intensely or persists as a “slow burn” for too long, it can wreak havoc around the body, said Dr. Braden Kuo, a neurogastroenterologist at Massachusetts General Hospital.

Here’s what scientists have learned so far about inflammation and the other factors driving these effects.

The Lungs