The mortality due to SARS-CoV-2 among CAR-T recipients approaches 40%. The efficacy of repeated vaccine doses, including bivalent booster, remains unknown. We examined the efficacy of repeated vaccine doses among CAR-T recipients who received at least 2 or more vaccine doses after cell infusion. This single-center retrospective study included adults >18 years receiving CAR-T for relapsed/refractory (R/R) B-cell hematologic malignancies targeting CD19, BCMA, or CD19 and CD20 between September 2018 through March 2022, and were alive beyond 2021 to receive incremental SARS-CoV-2 vaccine doses with available seroconversion data. Multivariable analyses were performed using the design-adjusted Cox regression and logistic regression approaches with stratification. In multivariable analysis, seroconversion rates were significantly greater with a total of 4 or more vaccine doses (OR 8.22, p=.008). CAR-T recipients with other B-cell HMs had significantly decreased seroconversion rates and diminished Ab titers compared to those with RRMM (OR 0.07, P=0.003). One patient died due to COVID-19 in this vaccinated study cohort, with a COVID-19-attirbutable mortality rate of 1.7%. The results provide baseline vaccine response data in a contemporary cohort including patients with diverse group of SARS-COV2 variants and support recent CDC guidelines in contending for repeated vaccinations directed against the prevalent variant of concern.