Fluctuations of SARS-CoV-2 Antibody Concentrations with Age in Vaccine Naïve Population with SARS-CoV- 2 Infection

Abstract

Abstract Introduction/Objective Notable differences have been observed in the severity of COVID-19 disease across age groups. This study’s aim was to investigate the antibody dynamics in children versus adults after natural infection with SARS-CoV-2. Methods/Case Report Charts of patients who had SARS-CoV-2 spike protein antibody (SPA) testing at our institution were reviewed. Patients with positive SPA and no documented evidence of SARS-CoV-2 vaccination were selected. SARS-CoV-2 nucleocapsid antibody (NA) testing was performed on the same SPA positive blood specimens to confirm that positive SPA was due to SARS-CoV-2 infection. In cases where NA testing could not be performed, SARS-CoV-2 polymerase chain reaction results were used to confirm previous infection. Patterns involving age, NA, and SPA concentrations were detected using scatter and box-and-whisker plots. Wilcoxon signed-rank tests were subsequently used to assess for statistical significance in the different age groups. This study was approved by our institution's IRB. Results (if a Case Study enter NA) There were 372 patients who had SPA testing and previous SARS-CoV-2 infection. SPA concentrations were not uniformly distributed but showed significantly higher concentrations in younger patients with a visually determined inflection point of around 20 years old. This was statistically confirmed by binning ages by decade of life and comparing their medians (p-value<0.05). Within the cohort, 107 patients were 20 years old or younger while 265 were older. Patients 0-20 years old had higher median SPA levels (262.9 U/mL vs. 108.2 U/mL, p-value<0.05) and significantly more variation (interquartile range 535 U/mL vs. 235 U/mL). NA levels showed a similar pattern in the overall distribution, but there was no statistically significant difference between the age groups (medians 45.835 U/mL vs. 30.3 U/mL, p-value=0.44). Conclusion These findings suggest that patients up to 20 years old have significantly higher SPA levels following SARS-CoV-2 infection, which may explain the milder symptoms of COVID-19 disease in children.