Fig. 3
Neutralizing and spike antibody titers after three vaccine doses, symptomatic and asymptomatic breakthrough infections
Shown are NAb titers against the original Wild-type strain (A), the Delta variant (B), and the Omicron BA.1 variant (C) determined by 50% focus reduction neutralization test (FRNT50) using the serum at follow-up. Also shown are anti-spike antibody titers measured with the Abbott reagent (D) and the Roche reagent (E) using the serum at follow-up
Patients with PCR-confirmed infection were all symptomatic (n = 7), while those with seropositive on any of anti-SARS-CoV-2 nucleocapsid protein assays (Abbott or Roche assays) at follow-up were all asymptomatic (n = 4)
The bars indicate geometric mean titers, and I-shaped bars indicate its geometric standard deviations. The dushed horizontal lines indicate the LOD for FRNT50 (NT50 < 40) and Roche assay (U/mL > 25,000) in the present analysis
Statistical significance was determined by Kruskal-Wallis and Dunn’s multiple comparison test (ns: not significant; *P < 0.05; **P < 0.01; ***P < 0.001)
Abbreviations: AU, arbitrary units; COVID-19, coronavirus disease 2019; LOD, limits of detection; NT50, 50% neutralization titer; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.