Clinical Utility of Sero-Immunological Responses Against SARS-CoV-2 Nucleocapsid Protein During Subsequent Prevalence of Wild-Type, Delta Variant, and Omicron Variant

Fig. 1. Summary of the number of samples used in this study. For each group, two numbers separated with a slash sign (/) were provided where the former and latter numbers indicate the number of samples and individuals, respectively. While only one sample was obtained from each individual in the humoral response analysis, multiple samples from an individual were used in the longitudinal evaluation and the cellular response analysis. COVID-19 = coronavirus disease 2019.

Fig. 2. Nucleocapsid antibody test results according to various clinical considerations. Distribution of nucleocapsid antibody results dissected into (A) non-IC (n = 240) and IC patients (n = 62); (B) wild-type (n = 108), delta (n = 40), and omicron (n = 92) samples in non-IC patients; (C) wild-type (n = 4), delta (n = 4), and omicron (n = 54) samples in non-IC patients; (D) mild-to-moderate (n = 164) and severe-to-critical (n = 76) non-IC patients; (E) wild-type (n = 78), delta (n = 8), and omicron (n = 78) samples in mild-to-moderate patients; (F) wild-type (n = 30), delta (n = 32), and omicron (n = 14) samples in severe-to-critical patients; (G) longitudinal evaluation of nucleocapsid antibody titers in 513 samples from 291 coronavirus disease 2019 patients. SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2, COI = cut-off index, IC = immunocompromised, WT = wild-type, Mod = moderate, Crit = critical.

Fig. 3. Cell-mediated immune response against SARS-CoV-2 nucleocapsid and spike proteins. (A) Distribution density plot of IFN-γ [N-Nil] results in non-infected healthcare workers (n = 431) and COVID-19 patients (n = 132); (B) IFN-γ results of vaccinees (n = 431); Longitudinal results of (C) IFN-γ [N-Nil] results and (D) IFN-γ [S-Nil] results in patients with SARS-CoV-2 infection (n = 132). ELISA = enzyme-linked immunosorbent assay, IFN = interferon, SARS-CoV-2 = severe acute respiratory distress syndrome coronavirus 2, N = nucleocapsid protein, S = spike protein.