Pre-existing immunity to SARS-CoV-2: the knowns and unknowns | Nature Reviews Immunology

Pre-existing immunity to SARS-CoV-2: the knowns and unknowns | Nature Reviews Immunology

Pre-existing immune response to SARS-CoV-2

The cells of 20-50% of people who have not had COVID-19 show some immune response to SARS-CoV-2. Scientists hypothesize that the T-cell reactivity in some people reflects exposure to other circulating ‘common cold’ coronaviruses (there’s no implication that SARS-CoV-2 existed in humans before the current pandemic). A similar effect seems to have occurred in the H1N1 influenza pandemic of 2009, when older people fared better than younger adults, possibly because of the circulation of a different H1N1 strain decades earlier. More research is needed to determine whether the immune response might change how people get COVID-19, or how it might influence epidemiological modelling.
Nature Reviews Immunology | 7 min read