Level and duration of IgG and neutralizing antibodies to SARS-CoV-2 in children with symptomatic or asymptomatic SARS-CoV-2 infection

Abstract

Background: There are presently conflicting data about level and duration of antibodies to SARS-CoV-2 in children after symptomatic or asymptomatic infection. Methods: We enrolled adults and children in a prospective 6-month study in the following categories: 1) symptomatic, SARS-CoV-2 PCR+ (SP+; children, n=8; adults, n=16), 2) symptomatic, PCR- or untested (children, n=27), 3) asymptomatic exposed (children, n=13) and 4) asymptomatic, no known exposure (children, n=19). Neutralizing and IgG antibodies to SARS-CoV-2 antigens and Spike protein variants were measured by multiplex serological assays. Results: All SP+ children developed nAb, whereas 81% of SP+ adults developed nAb. Decline in the presence of nAb over 6 months was not significant in symptomatic children (100% to 87.5%, p=0.32) in contrast to adults (81.3 to 50.0%, p=0.03). Among all children with nAb (n=22), nAb titers and change in titers over 6 months were similar in symptomatic and asymptomatic children. Levels of IgG antibodies in children to the SARS-CoV-2 Spike, RBD-1 and -2, nucleocapsid and N-terminal domain antigens and to Spike protein variants were similar to those in adults. IgG levels to primary antigens decreased over time in both children and adults, but levels to three of six Spike variants decreased only in children. Conclusions: Children with asymptomatic or symptomatic SARS-CoV-2 infection develop robust neutralizing antibodies that remain present longer than in adults but wane in titer over time, and broad IgG antibodies that also wane in level over time.