Pre-existing immunity to SARS-CoV-2: the knowns and unknowns

Nat Rev Immunol. 2020 Aug;20(8):457-458. doi: 10.1038/s41577-020-0389-z.


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.

Publication types

  • Research Support, N.I.H., Extramural
  • Review

MeSH terms

  • Betacoronavirus / immunology*
  • COVID-19
  • Coronavirus Infections / immunology*
  • Humans
  • Immunologic Memory / immunology
  • Pandemics
  • Pneumonia, Viral / immunology*
  • SARS-CoV-2
  • T-Lymphocytes / immunology
  • Vaccines / immunology


  • Vaccines