Detection of neutralization antibodies against SARS-CoV-2 variants D614G, Delta, and Omicron. (A) Heatmap summarizes the distribution of antispike antibody levels of each sample tested and their corresponding neutralizing activities against D614G, Delta, and Omicron antibody. (B) Bar chart showing the proportion of samples with positive or negative neutralization, split into 4 stratifications of antispike (anti-S) protein levels. (C) Odds ratio (OR) indicates the differences among patients with antispike levels between <1000 and ≥1000 AU/mL (top), or the differences between strains for those with an antispike protein level >1000 AU/mL (bottom), that is, the odds of a positive neutralizing antibody response against Delta was only 0.186 times the odds of that against D614G. The OR was adjusted for number of doses. (D) Determinants of neutralization response (positive/negative). The overall P values accounted for different variants, number of doses, serological responses (positive/negative), and antispike antibody levels. Antispike antibody levels per variant were not significant; that is, for all 3 variants, the patients with antispike antibody levels ≥1000 AU/mL were always consistently better than those with antispike antibody levels <1000 AU/mL. All other terms are statistically significant (having adjusted for the others). LCL, lower confidence limit; UCL, upper confidence limit.