Fig. 1.

Longitudinal change in antibody titers of 39 COVID-19 patients. Blood samples were obtained from 39 COVID-19 patients at several timepoints between 0 and 154 days after onset. IgG titers against the RBD (A), the ectodomain of the S protein (C), and the N protein (D); IgM titers against the RBD (B); and neutralization titers (E) were determined by performing an ELISA and a neutralization test using a wild-type virus. The maximum dilution of blood samples that gave a positive result in the ELISA or reduced the plaque number by more than 50% was selected as the ELISA or neutralization titer. Lines of the same color indicate data from the same patient. (F) Geometric mean antibody titers at the highest titer over the entire study period (black) and at least 60 days post-onset (gray). **, p<0.01 (paired t-test).