Quote Originally Posted by Mike T View Post
It looks like the T cells are "specific" for Covid 19, but they might be reacting to an identical or similar epitope - shape - on a different Coronavirus - so called cross reactivity. So they may not have been in contact with Covid 19, but one of the Coronaviruses that can cause the "common cold".
That isn't what they are saying.

New research from Karolinska Institutet and Karolinska University Hospital shows that many people with mild or asymptomatic COVID-19 demonstrate so-called T-cell-mediated immunity to the new coronavirus, even if they have not tested positively for antibodies. According to the researchers, this means that public immunity is probably higher than antibody tests suggest.