Age-associated variations in anti-spike antibody responses in mild SARS-CoV-2 disease.

Abstract Background: SARS-CoV-2 most severely affects older age groups, while children experience minimal disease. We measured elements of adaptive immunity in children and adults with SARS-CoV-2 to define the age-dependent viral and host response. Methods: Participants were enrolled in the Epidemiology, Immunology, and Clinical Characteristics of Emerging Infectious Diseases with Pandemic Potential (EPICC) study. Eligibility required that individuals present with COVID-19-like symptoms between March 2020 to March 2022. Magnitude of viral RNA was determined by quantitative PCR. SARS-CoV-2-specific antibodies were measured from blood with multiplex microsphere immunoassays. Results: Serologic responses against the spike protein were measured at early and convalescent time points and compared by age, predominant infecting SARS-CoV-2 variant, and vaccination status. In those with mild disease, the seropositivity rates did not differ based on age. The magnitude of the anti-spike IgG response differed by age at early time points. Only the oldest age group differed at convalescent time points. Conclusions: The serologic response to SAR-CoV-2 differs with age, implicating host immunity in pathogenesis. Improved understanding of the host immune response has the potential to optimize vaccine design. Disclaimer:The views expressed are those of the authors and do not reflect the official policy of the Department of the Army, Department of the Navy, the Department of the Air Force, the Department of Defense or the U.S. Government and the Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. (HJF). The investigators have adhered to the policies for protection of human subjects as prescribed in 45 CFR 46. This work was supported by the Defense Health Program (grant number HU00012020067) and the National Institute of Allergy and Infectious Diseases (grant number HU00011920111).