• Shidan Tosif, Melanie R Neeland, Philip Sutton, Paul V Licciardi, Sohinee Sarkar, Kevin J Selva, Lien Anh Ha Do, Celeste Donato, Quan TohZhengZ0000-0002-0282-5837Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia.Infection and Immunity, Murdoch Children's Research Institute, Melbourne, Australia., Rachel Higgins, Carolien Van de Sandt, Melissa M Lemke, Christina Y Lee, Suzanne K Shoffner, Katie L Flanagan, Kelly B Arnold, Francesca L Mordant, Kim Mulholland, Julie Bines, Kate Dohle, Daniel G Pellicci, Nigel Curtis, Sarah McNab, Andrew Steer, Richard Saffery, Kanta Subbarao, Amy W Chung, Katherine Kedzierska, David P Burgner, and Nigel W Crawford.
• Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia. Shidan.Tosif@rch.org.au.
• Nat Commun. 2020 Nov 11; 11 (1): 5703.

AbstractCompared to adults, children with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have predominantly mild or asymptomatic infections, but the underlying immunological differences remain unclear. Here, we describe clinical features, virology, longitudinal cellular, and cytokine immune profile, SARS-CoV-2-specific serology and salivary antibody responses in a family of two parents with PCR-confirmed symptomatic SARS-CoV-2 infection and their three children, who tested repeatedly SARS-CoV-2 PCR negative. Cellular immune profiles and cytokine responses of all children are similar to their parents at all timepoints. All family members have salivary anti-SARS-CoV-2 antibodies detected, predominantly IgA, that coincide with symptom resolution in 3 of 4 symptomatic members. Plasma from both parents and one child have IgG antibody against the S1 protein and virus-neutralizing activity detected. Using a systems serology approach, we demonstrate higher levels of SARS-CoV-2-specific antibody features of these family members compared to healthy controls. These data indicate that children can mount an immune response to SARS-CoV-2 without virological confirmation of infection, raising the possibility that immunity in children can prevent the establishment of SARS-CoV-2 infection. Relying on routine virological and serological testing may not identify exposed children, with implications for epidemiological and clinical studies across the life-span.

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