It is thought that mRNA-based vaccine-induced immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) wanes quickly, based mostly on short-term studies. Here, we analyzed the kinetics and durability of the humoral responses to SARS-CoV-2 infection and vaccination using >8,000 longitudinal samples collected over a 3-year period in New York City. Upon primary immunization, participants with pre-existing immunity mounted higher antibody responses faster and achieved higher steady-state antibody titers than naive individuals. Antibody kinetics were characterized by two phases: an initial rapid decay, followed by a stabilization phase with very slow decay. Booster vaccination equalized the differences in antibody concentration between participants with and without hybrid immunity, but the peak antibody titers decreased with each successive antigen exposure. Breakthrough infections increased antibodies to similar titers as an additional vaccine dose in naive individuals. Our study provides strong evidence that SARS-CoV-2 antibody responses are long lasting, with initial waning followed by stabilization. Display omitted •COVID-19-vaccine-induced immunity wanes but stabilizes at an individual setpoint•Pre-existing immunity results in rapid antibody responses upon vaccination•Boosters equalize antibody titers between individuals with and without hybrid immunity•Antibody kinetics show two phases: an initial rapid decay followed by a steady state SARS-CoV-2 mRNA-based vaccine-induced immunity is thought to wane quickly based on short-term studies. Using longitudinal data, Srivastava et al. find that participants with hybrid immunity show faster, higher antibody responses after initial vaccination, but boosters evened out differences. Modeling of antibody kinetics revealed an initial rapid decay followed by a stabilization phase, challenging the idea that vaccine immunity fades quickly.