Early life B cell responses and inflammation following SARS-CoV-2 infection

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Abstract As of March 2021, SARS-CoV-2 has caused more than 50 million infections and 2 million deaths, constituting an unprecedented pandemic in the modern world. While infected individuals rapidly develop IgG responses against the viral Spike after infection, some studies have indicated that individuals with mild infection generate weaker neutralizing Ab responses compared to those with severe disease. The durability of the immune response following natural infection and its afforded protection against subsequent infections and emerging related variants remain unclear. Interestingly, unlike other respiratory viruses, children are rarely develop severe disease following SARS CoV-2 infection. Antibody responses in hospitalized children and those who developed the multisystem inflammatory syndrome (MIS-C) have been characterized, but, there is a gap in knowledge of the magnitude, quality, durability, and breadth of antibody responses in asymptomatic or mildly symptomatic children, responses that may contribute to making children less susceptible to severe infection compared to adults. Moreover, the possibiltiy of reinfection or infection with a novel variant in previously-infected children is not known, making the possibility of restarting congregate settings for children without a childhood vaccine quite challenging. Our overarching goal is to characterize the kinetics, function, breadth, and durability of humoral immune responses elicited by SARS-CoV-2 infection across the pediatric age spectrum in comparison to that of adults. We hypothesize that pediatric immune responses to SARS-CoV-2 infection is distinct from that of adults, and associates with protection against symptomatic disease and durability of immunity. Using samples from two unique ongoing community studies of SARS-CoV-2 infections in adults and children, we will test our hypothesis through the following aims: 1) Define the similarities and differences in the kinetics, magnitude, specificity, function and durability of SARS-CoV-2-specific Ab responses in children and adults; 2) Investigate the breadth and potency of antibody responses in SARS- CoV-2-infected children against established and predicted variants of SARS-CoV-2; and 3) Define the SARS-CoV-2-specific B cell repertoire and characterize the potency of pediatric SARS CoV-2-specific monoclonal antibodies. These evaluations will identify immune correlates of protection against severe disease and provide insights for immunization strategies towards the long term control of SARS CoV-2 which will likely become an endemic pathogen.