Evaluation and comparison of four quantitative SARS-CoV-2 serological assays in COVID-19 patients and immunized healthy individuals, cancer patients, and patients with immunosuppressive therapy.

BACKGROUND: Semi-quantitative and quantitative immunoassays are the most commonly used methodology to evaluate immunity post immunization. OBJECTIVES: To compare four quantitative SARS-CoV-2 serological assays in COVID-19 patients and immunized healthy individuals, cancer patients, and patients with immunosuppressive therapy. STUDY DESIGN: 210 serological samples from COVID-19 infection and vaccination cohorts were used to create a serological sample repository. Serological methods from four manufacturers, namely Euroimmun, Roche, Abbott, and DiaSorin, were evaluated for quantitative, semi-quantitative, and qualitative antibody measurements. All four methods measure IgG antibodies against the SARS-CoV-2 spike receptor-binding domain and report the results in Binding Antibody Unit/mL (BAU/mL). A Total Error Allowable (TEa) of ±25% was chosen as the criteria to determine whether two methods are clinically equivalent quantitatively. Semi-quantitative results (titers) were derived using numeric antibody concentration divided by the cut-off value for each method. RESULTS: All paired quantitative comparisons demonstrated unacceptable performance. With ±25% as TEa, the best agreement was 74 (35.2% out of 210 samples) between Euroimmun and DiaSorin, whereas the lowest agreement was 11 (5.2% out of 210 samples) between Euroimmun and Roche. Antibody titers amongst all four methods were significantly different (p < 0.001). The highest titer difference from the same sample is between Roche and DiaSorin with a 1392-fold difference. On qualitative comparison, none of the paired comparison showed acceptable comparison (p < 0.001). CONCLUSIONS: Poor correlation exists between four evaluated assays, quantitatively, semi-quantitatively, and qualitatively. Further harmonization of assays is required to achieve comparable measurements.

Management of Patients With Glomerulonephritis During the COVID-19 Pandemic: Recommendations From the Canadian Society of Nephrology COVID-19 Rapid Response Team.

PURPOSE OF PROGRAM: This article will provide guidance on how to best manage patients with glomerulonephritis (GN) during the COVID-19 pandemic. SOURCES OF INFORMATION: We reviewed relevant published literature, program-specific documents, and guidance documents from international societies. An informal survey of Canadian nephrologists was conducted to identify practice patterns and expert opinions. We hosted a national webinar with invited input and feedback after webinar. METHODS: The Canadian Society of Nephrology (CSN) Board of Directors invited physicians with expertise in GN to contribute. Specific COVID-19-related themes in GN were identified, and consensus-based recommendations were made by this group of nephrologists. The recommendations received further peer input and review by Canadian nephrologists via a CSN-sponsored webinar. This was attended by 150 kidney health care professionals. The final consensus recommendations also incorporated review by Editors of the Canadian Journal of Kidney Health and Disease. KEY FINDINGS: We identified 9 areas of GN management that may be affected by the COVID-19 pandemic: (1) clinic visit scheduling, (2) clinic visit type, (3) provision of multidisciplinary care, (4) blood and urine testing, (5) home-based monitoring essentials, (6) immunosuppression, (7) other medications, (8) patient education and support, and (9) employment. LIMITATIONS: These recommendations are expert opinion, and are subject to the biases associated with this level of evidence. To expedite the publication of this work, a parallel review process was created that may not be as robust as standard arm's length peer review processes. IMPLICATIONS: These recommendations are intended to provide optimal care during the COVID-19 pandemic. Our recommendations may change based on the evolving evidence.