LAUSR

Rationale & Objective SARS-CoV-2 vaccine effectiveness and immunogenicity threshold associated with protection against COVID-19 related hospitalization or death in the dialysis population is unknown. Study Design Retrospective, observational study. Setting & Participants Adult patients receiving maintenance dialysis through a national dialysis provider without COVID-19 history treated between February 1, 2021 and December 18, 2021 with follow up through January 17, 2022. Predictor(s) SARS-CoV-2 vaccination status. Outcome(s) All SARS-CoV-2 infections, composite of hospitalization or death following COVID-19. Analytical Approach Logistic regression was used to determine COVID-19 case rates and vaccine effectiveness. Results Of 16,213 patients receiving dialysis during the study period, 12,278 (76%) were fully vaccinated, 589 (4%) were partially vaccinated and 3,346 (21%) were unvaccinated by the end of follow-up. Of 1,225 COVID-19 cases identified, 550 (45%) occurred in unvaccinated patients, while 891 (73%) cases occurring during the Delta period. Between pre-Delta period and Delta periods vaccine effectiveness against a severe COVID-19 related event (hospitalization or death) was 84% and 70%, respectively. In the subset of 3,202 vaccinated patients with at least one anti-spike IgG assessment, lower anti-spike IgG levels were associated with higher case rates per 10,000 days and adjusted hazard ratios for both infection and COVID-related hospitalization or death. Limitations Observational design, residual biases and confounding may exist. Conclusions Among maintenance dialysis patients, SARS-CoV-2 vaccination was associated with a lower risk of COVID-19 diagnosis and associated hospitalization or death. Among vaccinated patients, low anti-spike IgG level is associated with worse COVID-19 related outcomes.