Long covid: Why are some people sick months after the virus?

By Jessica Hamzelou

Shortness of breath is one of the most common symptoms of a long Covid

Secret Annex Productions / Getty Images

The argument for naturally preserved herd immunity as a solution to the coronavirus pandemic has returned in recent weeks. However, the spread of the virus among younger people, who are less likely to die from Covid-19, could be devastating. It is estimated that millions of people around the world could already live with "long covid" – a seemingly debilitating syndrome that follows coronavirus infection.

As personal stories of long-term problems accumulate, researchers and health officials learn more …