Sars-cov-2 testing & positivity among persons with & without hiv in 6 us cohorts

Background: The low susceptibility of children to severe illness with SARS-CoV- 2 infection could be related to distinct virus-host interactions. Some studies indicate that SARS-CoV-2 infected adults with mild symptoms rapidly lose their antibody responses, but the kinetics of the antibody response in children have been less studied. To evaluate the antibody response of SARS CoV-2 antibodies in infected children, we used samples from the Biospecimens from Respiratory Virus-Exposed Kids (BRAVE Kids) Study, a community-based prospective cohort study of children and adolescents with SARS-CoV-2 infection or exposure. Methods: Samples from 71 SARS-CoV-2 infected children (median age: 9.7 years, IQR 4-16) collected at enrollment (M0), 2 and 4 months after exposure (M2, M4) were analyzed. A Luminex-based multiplex binding assay was used to measure Ig isotype (IgG, IgM, IgA) and IgG subclass (IgG1, IgG3) against 7 SARS-CoV-2 epitopes: whole spike (S), subunit 1 (S1), S2, receptor binding domain (RBD), N-terminal domain (NTD), nucleocapsid (NC) and membrane (M). The ability of antibodies to block viral interaction with the human receptor ACE2 was evaluated by an ELISA-based assay, and neutralization was assessed in a pseudovirus assay. Results: At time of enrollment (median of 5 days after infection), all participants had detectable levels of IgM and IgA against at least one of the tested SARS-CoV-2 antigens, and 91% had detectable IgG levels. IgM and IgA levels declined with time, although all children still had detectable levels of anti-S IgM and IgA at M4. In contrast, IgG binding to all viral regions increased significantly at M2 and, at M4, most children maintained robust IgG response. IgG1 and IgG3 antibodies were detected against most antigens. ACE2 blocking increased at M2 as compared to M0, and at M2 the percent blocking was higher in younger children than in older children (Fig 1). Similarly, younger children had higher levels of anti-RBD IgG at M2, whereas older children showed higher levels of anti-RBD IgM. We found no differences in antibody profiles between asymptomatic and symptomatic children. Preliminary analysis in 4 children indicated that neutralizing antibody responses were still detectable at M4. Conclusion: SARS CoV-2 infected children develop robust antibody responses that are still detectable 4 months after infection. This suggests that children could respond well to SARS CoV-2 vaccination and highlights the need to test candidate vaccines in pediatric populations.