Seroresponse to SARS-CoV-2 Vaccines among Maintenance Dialysis Patients over 6 Months.

Background And Objectives: Although most patients receiving maintenance dialysis exhibit initial seroresponse to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination, concerns exist regarding the durability of this antibody response. This study evaluated seroresponse over time.

Design, Setting, Participants, & Measurements: This retrospective cohort study included patients on maintenance dialysis, from a midsize national dialysis provider, who received a complete SARS-CoV-2 vaccine series and had at least one antibody titer checked after full vaccination. IgG spike antibodies (anti-spike IgG) titers were assessed monthly with routine laboratory tests after vaccination; the semiquantitative assay reported a range between zero and ≥20 Index. Descriptive analyses compared trends over time by history of coronavirus disease 2019 (COVID-19) and vaccine type. Time-to-event analyses examined the outcome of loss of seroresponse (anti-spike IgG <1 Index or development of COVID-19). Cox regression adjusted for additional clinical characteristics.

Results: Among 1870 patients receiving maintenance dialysis, 1569 had no prior COVID-19. Patients without prior COVID-19 had declining titers over time. Among 443 recipients of BNT162b2 (Pfizer), median (interquartile range) anti-spike IgG titer declined from ≥20 (5.89 to ≥20) in month 1 after full vaccination to 1.96 (0.60-5.88) by month 6. Among 778 recipients of mRNA-1273 (Moderna), anti-spike IgG titer declined from ≥20 (interquartile range, ≥20 to ≥20) in month 1 to 7.99 (2.61 to ≥20) by month 6. The 348 recipients of Ad26.COV2.S (Janssen) had a lower titer response than recipients of an mRNA vaccine over all time periods. In time-to-event analyses, recipients of Ad26.COV2.S and mRNA-1273 had the shortest and longest time to loss of seroresponse, respectively. The maximum titer reached in the first 2 months after full vaccination was associated with durability of the anti-spike IgG seroresponse; patients with anti-spike IgG titer 1-19.99 had a shorter time to loss of seroresponse compared with patients with anti-spike IgG titer ≥20 (hazard ratio, 15.5; 95% confidence interval, 11.7 to 20.7).

Conclusions: Among patients receiving maintenance dialysis, vaccine-induced seroresponse wanes over time across vaccine types. Early titers after full vaccination are associated with the durability of seroresponse.