Figure 1.

Seropositivity and antibody levels. Results reflect anti-RBD antibody levels (signal to cut-off [S/CO] ratio) measured by the Beckman assay, unless otherwise indicated. A, Seropositivity in healthcare workers (HCWs) and immunocompromised participants. P values refer to comparisons between HCWs and immunocompromised participants (χ² test). Whiskers denote 95% confidence intervals. B, All antibody levels (seropositive and seronegative) in nonimmunocompromised HCWs and immunocompromised participants. C, Comparisons of antibody levels among only participants with positive results. P value determined by Wilcoxon rank-sum test. D, Decline in antibody levels per month following vaccination; whiskers denote 95% confidence intervals. E, Antibody levels stratified by vaccine type among all participants, after adjustment of age, time from vaccination, and underlying immunocompromising condition; whiskers denote 95% confidence intervals. F, Correlation of antibody levels measured by the Beckman (anti-RBD) and Bio-Rad Bio-Plex (anti-RBD) assays. Abbreviations: HIV, human immunodeficiency virus; RBD, receptor-binding domain; SOT, solid organ transplant.