Nat Rev Immunol. 2020 08 ;20(8):457-458. PMID: 32636479
Pre-existing immunity to SARS-CoV-2: the knowns and unknowns.
T cell reactivity against SARS-CoV-2 was observed in unexposed people; however, the source and clinical relevance of the reactivity remains unknown. It is speculated that this reflects T cell memory to circulating ‘common cold’ coronaviruses. It will be important to define specificities of these T cells and assess their association with COVID-19 disease severity and vaccine responses.