Background: The reduced immune response of maintenance hemodialysis patients to coronavirus disease 2019 (COVID-19) vaccines is a major concern.

Objectives: To analyze the late (6 months after full vaccination) antibody response and compare it to early post-vaccination titer.

Methods: We conducted a multicenter prospective study of 13 hemodialysis units in Israel.

Results: We demonstrated that the low titers observed among ESRD patients 2–3 months after vaccination with the Comirnaty vaccine (median 63.8 AU/ml) declined to critically lower values 6 months after full vaccination. (Mediananti S antibodies, 31 AU/ml). Seropositivity significantly declined among hemodialysis patients from 89% to 74% (P < 0.0001), although it did not significantly change among controls.

Conclusions: We recommend all patients on hemodialysis receive a booster COVID-19 vaccine 6 months after the second dose.