Originally Posted by UnderCenter

https://blogs.sciencemag.org/pipeline/archives/2020/07/15/new-data-on-t-cells-and-the-coronavirus

Growing evidence that T cells are generated after COVID infection and possible existing immunity in 50% of people who have never been exposed to either SARS or COVID. Also found that T cells from the original SARS are lasting for 17 years.

Highlights from group that did study:

1) Infection with SARS-CoV-2 induces virus-specific T cells.

2) Patients recovered from SARS 17 years ago still possess virus-specific memory T cells displaying cross-reactivity to SARS-CoV-2.

3) Over 50% of donors with no infection or contact with SARS-CoV-1/2 harbor expandable T cells cross-reactive to SARS-CoV-2 likely induced by contact or infection with other coronavirus strains.

These results might explain why so many people are asymptomatic and might also mean “herd immunity” could be reached at a lower infection rate due to pre existing immunity from exposure to other coronaviruses.

Link to new study published today:
https://www.nature.com/articles/s41586-020-2550-z