Background and objectives Patients receiving hemodialysis are at high risk for both SARS-CoV-2 infection and severe COVID-19 disease. A life-saving vaccine is available, but sensitivity to vaccines is generally lower in dialysis patients. Little is yet known about antibody responses after COVID-19 vaccination in this vulnerable group. Design, setting, participants, and measurements In this prospective single-center study, we included 22 dialysis patients and 46 healthy controls from Heidelberg University Hospital between December 2020 and February 2021. We measured anti-S1 IgG with a threshold index for detection >1, neutralizing antibodies with a threshold for viral neutralization of ≥30% and antibodies against different SARS-CoV-2 fragments 17-22 days after the first and 18-22 days after the second dose of the mRNA vaccine BNT162b2. Results After the first vaccine dose, 4/22 (18%) dialysis patients compared with 43/46 (93%) healthy controls developed positive anti-S1 IgG, with a median (IQR) anti-S1 IgG index of 0.2 (0.1-0.7) compared with 9 (4-16), respectively. SARS-CoV-2 neutralizing antibodies exceeded the threshold for neutralization in 4/22 (18%) dialysis patients compared with 43/46 (93%) in healthy controls, with a median (IQR) percent inhibition of 11 (3-24) compared with 65 (49-75), respectively. After the second dose, 14/17 (82%) of dialysis patients developed neutralizing antibodies exceeding the threshold for viral neutralization and antibodies against the receptor-binding S1-domain of the spike protein, compared to 46/46 (100%) of healthy controls, respectively. The median (IQR) percent inhibition was 51 (32-86) compared to 98 (97-98) in healthy controls. Conclusions Patients receiving long-term hemodialysis show a reduced antibody response to the first and second doses of the mRNA vaccine BNT162b2. The majority (82%) develop neutralizing antibodies after the second dose, but at lower levels than healthy controls.

/pdf/early-humoral-responses-of-hemodialysis-patients-after-covid-1bs1gcgeir.pdf

Early Humoral Responses of Hemodialysis Patients after COVID-19 Vaccination with BNT162b2.

https://doi.org/10.1016/j.talanta.2022.123409

Review of COVID-19 testing and diagnostic methods

Heterologous ChAdOx1 nCoV-19/BNT162b2 Prime-Boost Vaccination Induces Strong Humoral Responses among Health Care Workers.

http://www.amjtransplant.org/article/S1600613522082764/pdf

Neutralizing antibody response against the B.1.617.2 (delta) and the B.1.1.529 (omicron) variants after a third mRNA SARS-CoV-2 vaccine dose in kidney transplant recipients

Antibody response after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination is impaired in kidney transplant recipients. Emerging variants, such as B.1.617.2 (δ), are of particular concern because of their higher transmissibility and partial immune escape. Little is known about protection against these variants in immunocompromised patients.In this prospective two-center study, antispike 1 IgG and surrogate neutralizing antibodies were measured in 173 kidney transplant recipients and 166 healthy controls with different vaccination schedules. In addition, different SARS-CoV-2 epitope antibodies from 135 vaccinated kidney transplant recipients were compared with antibodies in 25 matched healthy controls after second vaccination. In 36 kidney transplant recipients with seroconversion, neutralization against B.1.1.7 (α), B.1.351 (β), and B.1.617.2 (δ) was determined on VeroE6 cells and compared with neutralization in 25 healthy controls.Kidney transplant recipients had significantly lower seroconversion rates compared with healthy controls. After the second vaccination, antispike 1, antireceptor-binding domain, and surrogate neutralizing antibodies were detectable in 30%, 27%, and 24% of kidney transplant recipients, respectively. This compares with 100%, 96%, and 100% in healthy controls, respectively (P<0.001). Neutralization against B.1.1.7 was detectable in all kidney transplant recipients with seroconversion, with a median serum dilution that reduces infection of cells by 50% of 80 (interquartile range, 80-320). In contrast, only 23 of 36 (64%) and 24 of 36 (67%) kidney transplant recipients showed neutralization against B.1.351 and B.1.617.2, respectively, with median serum dilutions that reduce infection of cells by 50% of 20 (interquartile range, 0-40) and 20 (interquartile range, 0-40), respectively. Neutralization against different variants was significantly higher in healthy controls (P<0.001), with all patients showing neutralization against all tested variants.Seroconverted kidney transplant recipients show impaired neutralization against emerging variants of concern after standard two-dose vaccination.Observational study to assess the SARS-CoV-2 specific immune response in kidney transplant recipients (COVID-19 related immune response), DRKS00024668. 

Neutralization of SARS-CoV-2 Variants of Concern in Kidney Transplant Recipients after Standard COVID-19 Vaccination

Background Transplant recipients who develop COVID-19 may be at increased risk for morbidity and mortality. Determining the status of antibodies against SARS-CoV-2 in both candidates and recipients will be important to understand the epidemiology and clinical course of COVID-19 in this population. While there are multiple tests to detect antibodies to SARS-CoV-2, their performance is variable. Tests vary according to their platforms and the antigenic targets which make interpretation of the results challenging. Furthermore, for some assays, sensitivity and specificity are less than optimal. Additionally, currently available serological tests do not exclude the possibility that positive responses are due to cross reactive antibodies to community coronaviruses rather than SARS-CoV-2. Methods This study describes the development and validation of a high-throughput multiplex antibody detection assay. Results The multiplex assay has the capacity to identify, simultaneously, patient responses to 5 SARS-CoV-2 proteins, namely, the full spike protein, 3 individual domains of the spike protein (S1, S2, and receptor binding domain), and the nucleocapsid protein. The antibody response to the above proteins are SARS-CoV-2-specific, as antibodies against 4 common coronaviruses do not cross-react. Conclusions This new assay provides a novel tool to interrogate the spectrum of immune responses to SAR-CoV-2 and is uniquely suitable for use in the transplant setting. Test configuration is essentially identical to the single antigen bead assays used in the majority of histocompatibility laboratories around the world and could easily be implemented into routine screening of transplant candidates and recipients.

Development and Validation of a Multiplex, Bead-Based Assay to Detect Antibodies Directed Against SARS-CoV-2 Proteins.

Combining one‐step Sanger sequencing with phasing probe hybridization for HLA class I typing yields rapid, G‐group resolution predicting 99% of unique full length protein sequences

Transplant recipients who develop COVID-19 may be at increased risk for morbidity and mortality. Determining antibody status against SARS-CoV-2 in candidates and recipients will be important to understand the epidemiology and clinical course of COVID-19 infection in this population. There are multiple antibody tests to detect antibodies to SARS-CoV-2, but their performance varies according to their platforms and the antigenic targets, making interpretation of the results challenging. Additionally, currently available serological tests do not exclude the possibility that positive responses are due to cross reactive antibodies to community coronaviruses. This study describes the development and validation of a high throughput multiplex bead based antibody detection assay with the capacity to identify, simultaneously, patient responses to five distinct SARS-CoV-2 proteins. The antibody response to these proteins are SARS-CoV-2 specific as antibodies against four community coronaviruses do not cross-react. Assay configuration is essentially identical to the single antigen bead assays used in the majority of histocompatibility laboratories around the world and could easily be implemented into routine screening of transplant candidates and recipients. This new assay provides a novel tool to interrogate the spectrum of immune responses to SAR-CoV-2 and is uniquely suitable for use in the transplant setting.

/pdf/development-and-validation-of-a-multiplex-bead-based-assay-4p1k811gls.pdf

Peter Brescia

Papers

Development and Validation of a Multiplex, Bead-Based Assay to Detect Antibodies Directed Against SARS-CoV-2 Proteins.

Combining one‐step Sanger sequencing with phasing probe hybridization for HLA class I typing yields rapid, G‐group resolution predicting 99% of unique full length protein sequences

Development and validation of a multiplex bead based assay for the detection of antibodies directed against SARS-CoV-2 proteins