SARS-CoV-2 specific T cell responses are lower in children and increase with age and time after infection

• Published in: Nature communications Vol. 12; no. 1; pp. 4678 - 14
• Main Authors: Cohen, Carolyn A., Li, Athena P. Y., Hachim, Asmaa, Hui, David S. C., Kwan, Mike Y. W., Tsang, Owen T. Y., Chiu, Susan S., Chan, Wai Hung, Yau, Yat Sun, Kavian, Niloufar, Ma, Fionn N. L., Lau, Eric H. Y., Cheng, Samuel M. S., Poon, Leo L. M., Peiris, Malik, Valkenburg, Sophie A.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 29.07.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 13/1; 13/21; 13/31; 631/250/2152/1566; 631/250/255/2514; Adults; Antibodies; CD4 antigen; CD8 antigen; Cell activation; Children; Coronaviruses; COVID-19; Cytokines; Humanities and Social Sciences; Immune system; Immunity; Immunological memory; Immunology; Infections; Inflammation; Lymphocytes; Lymphocytes T; Memory cells; Monocytes; multidisciplinary; Ordination; Pathogenesis; Proteins; Science; Science (multidisciplinary); Severe acute respiratory syndrome coronavirus 2; Viral diseases
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-021-24938-4

SARS-CoV-2 infection of children leads to a mild illness and the immunological differences with adults are unclear. Here, we report SARS-CoV-2 specific T cell responses in infected adults and children and find that the acute and memory CD4 + T cell responses to structural SARS-CoV-2 proteins increase with age, whereas CD8 + T cell responses increase with time post-infection. Infected children have lower CD4 + and CD8 + T cell responses to SARS-CoV-2 structural and ORF1ab proteins when compared with infected adults, comparable T cell polyfunctionality and reduced CD4 + T cell effector memory. Compared with adults, children have lower levels of antibodies to β-coronaviruses, indicating differing baseline immunity. Total T follicular helper responses are increased, whilst monocyte numbers are reduced, indicating rapid adaptive co-ordination of the T and B cell responses and differing levels of inflammation. Therefore, reduced prior β-coronavirus immunity and reduced T cell activation in children might drive milder COVID-19 pathogenesis. Why children are generally less susceptible than adults to COVID-19 is unclear and has not extensively been examined longitudinally. Here the authors compare antibodies, cytokines and immune cell responses in adults and children over 6 months post-infection showing, among other things, a reduced CD4+ and CD8+ T cell response in children.