Regarding antispike assay, all 74 antinucleocapsid-positive specimens were also antispike positive, except for two (3%) patients, who repeatedly tested unfavorable for antispike antibodies despite being positive for antinucleocapsid antibodies. preventive approaches against COVID-19 in patients on LM22A-4 hemodialysis. Keywords: hemodialysis, SARS-CoV-2, serology, SARS-CoV-2 antibody, COVID-19 Abstract Background The humoral response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the hemodialysis population, including its dynamics over time, remains poorly understood. Methods To analyze initial and long-term humoral responses against SARS-CoV-2 in a hemodialysis population, we retrospectively evaluated findings from SARS-CoV-2 IgG serologic assays targeting the nucleocapsid antigen or spike antigen up to 6 months of follow-up in patients on hemodialysis in the Paris, France, region who had recovered from coronavirus disease 2019 (COVID-19). Results Our analysis included 83 patients (median age 65 years); 59 (71%) were male and 28 (34%) had presented with severe COVID-19. We observed positive initial SARS-CoV-2 IgG antinucleocapsid serology in 74 patients (89%) at a median of 67 days postdiagnosis. By multivariable analysis, immunocompromised status was the only factor significantly associated with lack of an IgG antinucleocapsid antibody response. Follow-up data were available at 6 months postdiagnosis for 60 of 74 patients (81%) with positive initial antinucleocapsid serology, and 15 (25%) of them had unfavorable antinucleocapsid serology at month 6. In total, 14 of 15 sera were tested for antispike antibodies, 3 of 14 (21%) of which were also negative. Overall, 97% of antinucleocapsid-antibodyCpositive specimens were also antispike-antibody positive. Female sex, age >70 years, and nonsevere clinical presentation were independently associated with faster IgG antinucleocapsid titer decay in multivariable analysis. After adjustment for sex and age >70 years, nonsevere clinical presentation was the only factor associated with faster decay of IgG antispike antibodies. Conclusions This study characterizes evolution of the SARS-CoV-2 antibody response in patients on hemodialysis and identifies factors that are associated with lack of seroconversion and with IgG titer decay. Keywords: hemodialysis, SARS-CoV-2, serology, SARS-CoV-2 antibody, COVID-19 Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) contamination, is associated with a severe risk of mortality in patients on hemodialysis.1,2 The Rabbit polyclonal to POLR2A humoral response against SARS-CoV-2 in the hemodialysis population, including its dynamics over time, remains poorly understood.3,4 Given the pandemics ongoing waves of new infections and the need for future vaccination strategies, the characterization of this response appears to be an important unmet need. In this study, we analyzed the initial and long-term humoral response against SARS-CoV-2 in a hemodialysis population. Methods In this LM22A-4 multicenter study, the study population included 83 patients undergoing hemodialysis in the Paris, France, area who had recovered from COVID-19; 76 patients were previously described. 2 Clinical data were retrospectively recorded. A severe form of COVID-19 was defined by the need for oxygen therapy. Immunocompromised status was characterized by one of the following factors: former organ transplant, HIV contamination, recent (within <6 months) immunosuppressive therapy, or chemotherapy. We collected 241 sequential serum samples, which were analyzed with the Abbot SARS-CoV-2 IgG Architect system (targeting the nucleocapsid antigen). Of the 83 participants, 25 had two serial measurements of IgG levels, and 52 had at least three serial measurements. We used the Ortho Clinical Diagnostics Vitros IgG assay (targeting the spike antigen) to analyze 113 samples. Data collection was declared to the French Commission rate Nationale de lInformatique et des Liberts, registration 2218583. This protocol was submitted to the approbation of Paris Centre Institutional Review LM22A-4 Board. Statistical Analyses Categorical and continuous variables were expressed as count (percentage) and median (interquartile range, IQR), respectively. When LM22A-4 appropriate, chi-squared or Fishers exact tests were used for categorical comparison, and test or MannCWhitney for continuous variables. Variables associated with seroconversion were analyzed by logistic regression. All variables with a value <0.2 in univariable analysis were included in the multivariable analysis. Stepwise backward selection on the basis of the Akaike information criterion was then used for the final multivariable model. In the subset of patients who experienced seroconversion, we modeled the SARS-CoV-2 antibody decay with random-intercept linear.