Change in serum measles IgG concentrations after CD19-CARTx. (A) Spaghetti plot of serum measles IgG concentrations before and after CD19-CARTx; 63 measles IgG measurements were obtained for 22 participants. Each line represents 1 participant. A dashed reference line is shown at 110 mIU/mL, the concentration above which an individual is considered seroprotected for measles. Negative and indeterminate results were based on values ≤90 mIU/mL and values between 91 and 109 mIU/mL, respectively. (B) Forest plot showing linear mixed-effects model estimates for the mean change in serum measles IgG concentrations. Exploratory subgroup estimates were computed from separate models, including the subgroup variable, the time period (post– vs pre–CD19-CARTx), and their interaction. Underlying disease was not included because of the limited sample size for each disease group. Additional data are presented from models excluding 1 outlier who seroreverted (blue boxes). In the model excluding the participant who seroreverted, participants without a prior HCT had a greater decrement in measles IgG concentrations than did those with a prior HCT (interaction P = .009). Squares represent the change estimates, and bars indicate the 95% CIs. Dashed vertical reference lines are shown at our prespecified noninferiority margin and at no change. For both panels, we excluded data from samples obtained ≤16 weeks after IVIG administration and from participants lacking seroprotective measles IgG pre–CD19-CARTx (n = 8). LCL, lower confidence limit of the 95% CI; UCL, upper confidence limit of the 95% CI.