Longitudinal Characterization of SARS-CoV-2 Immunity in Hemodialysis Patients Post Omicron

Individuals receiving hemodialysis (HD) are at risk for severe COVID-19 and have attenuated responses to COVID-19 vaccines. Evolution of immunity and risk for subsequent infection with additional vaccinations and infections in this population is poorly understood.

An observational multicenter cohort of 55 patients receiving HD in community HD centers, majority (85%) with at least 2 doses of COVID-19 vaccine (56% female, age [median; interquartile range, IQR] of 67, [58.0-74.0] years), was followed-up with for 50 weeks between December, 2021 and April, 2023 and collected blood samples at enrollment, 8 weeks, and 24 weeks thereafter. Anti-SARS-CoV-2 IgG and ACE2 inhibition (surrogate neutralization) against ancestral, Delta, and Omicron subvariants was measured. T-cell responses to Spike and Mucleocapsid proteins were measured via enzyme-linked immunosorbent spot. Changes in antibody and T cell responses were assessed by paired Wilcoxon rank-sum testing and Fisher exact testing. Antibody responses were compared to thrice vaccinated healthy controls (HCs) as a benchmark for what optimal responses could have been in the early Omicron period.

Neutralization did not increase over time, and HD participants had lower neutralization than HCs. Only 56% of HD participants had a positive T cell response to spike after the BA.1/2 wave. Antibody and cellular responses were concordant in only 34.5% at final visit. Antibody responses trended higher among those with prior COVID-19, but spike-specific T cell responses did not vary.

Original vaccine formulations and previous infection are insufficient to induce reliable SARS-CoV-2 responses in individuals on HD, suggesting that updated annual COVID-19 vaccines and transmission-based precautions remain critical in this population.