In rare cases, the delta variant of the coronavirus is causing vaccinated people to get sick — so-called "breakthrough infections." Now researchers are asking: Could these infections lead to long COVID, when symptoms last weeks and months? Today, science correspondent Rob Stein makes sense of the latest data, explaining what we know so far about long COVID in vaccinated people.Read more of Rob's reporting here: https://www.npr.org/sections/health-shots/2021/09/13/1032844687/what-we-know-about-breakthrough-infections-and-long-covid