High antibody levels and reduced cellular response in children up to one year after SARS-CoV-2 infection

Severity of SARS-CoV-2 infection is different in adults and children which involves the immune response. Here using a parent and children cohort with 4 month and 12 month sampling times, the authors show enhanced levels and increased breadth of anti-spike antibody level over time but reduced specific T cell and B cell numbers in children. The COVID-19 course and immunity differ in children and adults. We analyzed immune response dynamics in 28 families up to 12 months after mild or asymptomatic infection. Unlike adults, the initial response is plasmablast-driven in children. Four months after infection, children show an enhanced specific antibody response and lower but detectable spike 1 protein (S1)-specific B and T cell responses than their parents. While specific antibodies decline, neutralizing antibody activity and breadth increase in both groups. The frequencies of S1-specific B and T cell responses remain stable. However, in children, one year after infection, an increase in the S1-specific IgA class switch and the expression of CD27 on S1-specific B cells and T cell maturation are observed. These results, together with the enhanced neutralizing potential and breadth of the specific antibodies, suggest a progressive maturation of the S1-specific immune response. Hence, the immune response in children persists over 12 months but dynamically changes in quality, with progressive neutralizing, breadth, and memory maturation. This implies a benefit for booster vaccination in children to consolidate memory formation.

Automated summary

The severity and immune response of SARS-CoV-2 infection differ in adults and children. Children show a plasmablast-driven initial response, enhanced specific antibody response, and lower but detectable specific B and T cell responses compared to their parents. After one year, children exhibit an increase in S1-specific IgA class switch and enhanced T cell maturation.