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

• Published in: Nature reviews. Immunology Vol. 20; no. 8; pp. 457 - 458
• Main Authors: Sette, Alessandro, Crotty, Shane
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-08-2020; Nature Publishing Group
• Subjects: 631/250/255/2514; 631/250/590; Betacoronavirus - immunology; Biomedical and Life Sciences; Biomedicine; Comment; Common cold; Coronaviridae; Coronavirus Infections - immunology; Coronaviruses; COVID-19; Herd immunity; Humans; Immunologic Memory - immunology; Immunological memory; Immunology; Lymphocytes; Lymphocytes T; Medical research; Medicine, Experimental; Memory cells; Pandemics; Pneumonia, Viral - immunology; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; T cells; T-Lymphocytes - immunology; Vaccine development; Vaccines; Vaccines - immunology
• ISSN: 1474-1733; 1474-1741; 1474-1741
• 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.
Recent studies have shown T cell reactivity to SARS-CoV-2 in 20–50% of unexposed individuals; it is speculated that this is due to T cell memory to common cold coronaviruses. Here, Crotty and Sette discuss the potential implications of these findings for disease severity, herd immunity and vaccine development.