Durability of SARS-CoV-2 spike antibody levels in dialysis patients after COVID-19 infection

Background: Durability of SARS-CoV-2 receptor-binding domain spike antibody (RBD s-Ab) levels among patients receiving dialysis after COVID-19 [WDE1] is unknown[EL2] beyond 6 months. We describe the persistence (index value ≥ 1 and ≥ 2 U/L) of semi-quantitative RBD s-Ab levels in dialysis patients over 14 month period. Methods: All maintenance dialysis patients (≥18 years old) within Dialysis Clinic, Inc. 260 clinics in 28 states with COVID-19 infection history and RBD s-Ab levels determined between Jan 1 and May 23, 2021 were included. On the day of RBD s-Ab level determination, patient demographics (age, sex, race, modality, ESKD vintage) and days since COVID-19 diagnosis were determined. Patient RBD s-Ab levels obtained after COVID-19 vaccination were excluded. Results: A total of 515 patients, mean age 62±14 years, 57% male, 46% White, 94% HD and vintage 4.6±4.4 years[EL1], [HJM2] had 835 RBD s-Ab levels assessed at a median of 59 days (range 0-422 days) post COVID-19 diagnosis. RBD s-Ab levels were assessed 1, 2 or ≥3 times in 64%, 18% and 18% patients, respectively. Only 32 (6.2%) patients had undetectable RBD s-Ab on the last draw. A cross sectional summary of the last available RBD s-Ab levels suggests that titers remain detectable for long duration (Figure[EL3] [HJM4]). In patients (N=186;36%) with multiple RBD s-Ab levels (mean 28±15;median 28 days between levels), subsequent values were higher, lower [EL5] [HJM6] or unchanged 7%, 16% and 77% of time[EL7], respectively. Conclusions: Most maintenance dialysis patients sampled developed SARS-CoV-2 RBD s-Ab after COVID diagnosis, and durability extends up to 14 months. Further elucidation of longitudinal RBD s-Ab values post-COVID-19 infection as well as after completing vaccination for SARS-CoV-2 is needed.