SARS-CoV-2 vaccine effectiveness and breakthrough infections in maintenance dialysis patients

BackgroundSARS-CoV-2 vaccine effectiveness during the Delta period and immunogenicity threshold associated with protection against COVID-19 related hospitalization or death in the dialysis population is unknown. MethodsA retrospective, observational study assessed SARS-CoV-2 vaccine effectiveness and immunogenicity threshold in all adult maintenance dialysis patients without COVID-19 history treated between February 1 and October 2, 2021. All COVID-19 infections, composite of hospitalization or death following COVID-19 and available SARS-CoV-2 anti-spike immunoglobulin (Ig) G values were extracted from electronic medical record. COVID-19 cases per 10,000 days at risk and vaccine effectiveness during pre-Delta and Delta periods were determined. ResultsOf 15,718 patients receiving dialysis during the study period, 11,191 (71%) were fully vaccinated, 733 (5%) were partially vaccinated and 3,794 (24%) were unvaccinated. 967 COVID-19 were cases identified: 511 (53%) occurred in unvaccinated patients and 579 (60%) occurred during the Delta period. COVID-19 related hospitalization or death was less likely among vaccinated versus unvaccinated patients for all vaccines (adjusted HR 0.19 [0.12, 0.30]) and for BNT162b2/Pfizer, mRNA-1273/Moderna, and Ad26.COV2.S/Janssen (adjusted HR=0.25 [0.16, 0.40], 0.14 [0.08, 0.22], and 0.34 [0.17, 0.68] respectively). Among those with anti-spike IgG levels, those with IgG level [≥] 7 had significantly lower risk of a COVID-19 diagnosis (HR=0.25 [0.15, 0.42]) and none experienced a COVID-related hospitalization or death. ConclusionsAmong 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. Significance StatementSARS-CoV-2 vaccine effectiveness and association between antibody levels and clinical outcomes in maintenance dialysis patients is not known. Between February 1 and October 2, 2021, vaccine effectiveness was 85% against COVID-19 infection and 81% against composite of COVID-related hospitalization or death. COVID-19 case rates and severe outcomes were higher during the Delta dominant period (June 27-October 2, 2021). Increasing time (weeks) since full vaccination status was associated with increased risk for COVID-19 related hospitalization or death. Anti-spike IgG level [≥] 7 had lower risk of a COVID-19 diagnosis and no COVID-related hospitalization or death. Our findings supports utilization of SARS-CoV-2 vaccination and suggests that monitoring SARS-CoV-2 antibody levels and administering additional vaccine doses to maintain adequate immunity will be beneficial.