2/ Our 1st scientific paper showed that ~50% of unexposed people have T cells that recognized SARS-CoV-2 already https://t.co/hbaRuPUfL3. The most obvious conclusion was these were memory T cells from previous common cold coronavirus infections, but that was not directly shown. pic.twitter.com/J22CnJtQId

— Prof. Shane Crotty (@profshanecrotty) August 12, 2020