Anand Swaminathan, MD and Isaac Bogosh, MD
Sette, A., Crotty, S. Pre-existing immunity to SARS-CoV-2: the knowns and unknowns. Nat Rev Immunol 20, 457–458 (2020). https://doi.org/10.1038/s41577-020-0389-z
Grifoni, Alba et al.Targets of T Cell Responses to SARS-CoV-2 Coronavirus in Humans with COVID-19 Disease and Unexposed Individuals. Cell, Volume 181, Issue 7, 1489 - 1501.e15. https://doi.org/10.1016/j.cell.2020.05.015
David S. - August 26, 2020 1:50 PM
Ian L. - August 26, 2020 4:37 PM
There ought be patients who have had blood taken prior to a COVID 19 diagnosis who had an asymptomatic or mild disease who can have their T cell cross reactivity tested .
Futher you could test plain antibodies to other coronovirus subtypes.