Association of Age With SARS-CoV-2 Antibody Response
Authors: He S. Yang, Victoria Costa, Sabrina E. Racine-Brzostek, Karen P. Acker, Jim Yee, Zhengming Chen, Mohsen Karbaschi, Robert Zuk, Sophie Rand, Ashley Sukhu, P. J. Klasse, Melissa M. Cushing, Amy Chadburn, Zhen Zhao
Journal: JAMA Network Open (2021)

<h3>Importance</h3> Accumulating evidence suggests that children infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are more likely to manifest mild symptoms and are at a lower risk of developing severe respiratory disease compared with adults. It remains unknown how the immune response in children differs from that of adolescents and adults. <h3>Objective</h3> To investigate the association of age with the quantity and quality of SARS-CoV-2 antibody responses. <h3>Design, Setting, and Participants</h3> This cross-sectional study used 31 426 SARS-CoV-2 antibody test results from pediatric and adult patients. Data were collected from a New York City hospital from April 9 to August 31, 2020. The semiquantitative immunoglobin (Ig) G levels were compared between 85 pediatric and 3648 adult patients. Further analysis of SARS-CoV-2 antibody profiles was performed on sera from 126 patients aged 1 to 24 years. <h3>Main Outcomes and Measures</h3> SARS-CoV-2 antibody positivity rates and IgG levels were evaluated in patients from a wide range of age groups (1-102 years). SARS-CoV-2 IgG level, total antibody (TAb) level, surrogate neutralizing antibody (SNAb) activity, and antibody binding avidity were compared between children (aged 1-10 years), adolescents (aged 11-18 years), and young adults (aged 19-24 years). <h3>Results</h3> Among 31 426 antibody test results (19 797 [63.0%] female patients), with 1194 pediatric patients (mean [SD] age, 11.0 [5.3] years) and 30 232 adult patients (mean [SD] age, 49.2 [17.1] years), the seroprevalence in the pediatric (197 [16.5%; 95% CI, 14.4%-18.7%]) and adult (5630 [18.6%; 95% CI, 18.2%-19.1%]) patient populations was similar. The SARS-CoV-2 IgG level showed a negative correlation with age in the pediatric population (<i>r</i> = −0.45,<i>P</i> &lt; .001) and a moderate but positive correlation with age in adults (<i>r</i> = 0.24,<i>P</i> &lt; .001). Patients aged 19 to 30 years exhibited the lowest IgG levels (eg, aged 25-30 years vs 1-10 years: 99 [44-180] relative fluorescence units [RFU] vs 443 [188-851] RFU). In the subset cohort aged 1 to 24 years, IgG, TAb, SNAb and avidity were negatively correlated with age (eg, IgG:<i>r</i> = −0.51; P &lt; .001). Children exhibited higher median (IQR) IgG levels, TAb levels, and SNAb activity compared with adolescents (eg, IgG levels: 473 [233-656] RFU vs 191 [82-349] RFU;<i>P</i> &lt; .001) and young adults (eg, IgG levels: 473 [233-656] RFU vs 85 [38-150] RFU;<i>P</i> &lt; .001). Adolescents also exhibited higher median (IQR) TAb levels, IgG levels, and SNAb activity than young adults (eg, TAb levels: 961 [290-2074] RFU vs 370 [125-697];<i>P</i> = .006). In addition, children had higher antibody binding avidity compared with young adults, but the difference was not significant. <h3>Conclusions and Relevance</h3> The results of this study suggest that SARS-CoV-2 viral specific antibody response profiles are distinct in different age groups. Age-targeted strategies for disease screening and management as well as vaccine development may be warranted.