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1. Graphpad prism 4 parameter logistic curve fit verification#
2. Graphpad prism 4 parameter logistic curve fit trial#

Furthermore, by the beginning of March 2021, there have been in total 266 confirmed and probable cases of a “South Africa” variant (VOC 202012/V2 (B.1.351). However, since January 2021, the “UK variant” (VOC 202012/V1 or B1.1.7) has become the predominant virus in the United Kingdom ( 9). The main SARS CoV-2 lineage circulating in the autumn of 2020 in the United Kingdom was B.1.177 (the Spanish lineage). This study evaluated several assay performance criteria (such as precision and sensitivity) using recognized and standardized evaluation protocols (EPs) for the new Abbott SARS-CoV-2 IgG II Quant method on the Alinity i system (Abbott Diagnostics, Chicago, IL, USA) and explored the different materials available that may form the basis of a candidate international reference standard for harmonization programs ( 6).Īs the pandemic progresses, new variants of the virus emerge, raising concern that the mutations in these variants may render immunoassays ineffective, as the antigenic changes that arise may no longer represent the antigenic regions of the reagents in the assay. To do this, two elements are required: a robust quantitative SARS-CoV-2 IgG method, which is directed against the spike protein, and a commutable standard or reference material to allow comparison of results across different methods and thus different trials or immunization programs ( 5). With the introduction of a national immunization program, it will be important to understand the antibody response to immunization in terms of development, peak concentration, and decline over time to assess efficacy of the vaccination delivery.

Graphpad prism 4 parameter logistic curve fit trial#

While there is trial data for each of the vaccines in use, there are limited data regarding the quantitative changes in antibody concentrations over time following vaccination. In the United Kingdom, a national immunization program has been launched, with a tiered system of invitations to receive the vaccine dependent on risk of a negative outcome from the disease ( 4). Although there are several different approaches to the design of these vaccines, a common factor is the use of the spike proteins, in the form of the attenuated whole virus, or portions of the spike protein such as the receptor binding domain or through the use of nucleic acids directed to the synthesis of the spike protein. The development and delivery of a range of vaccines against the virus is under way, with several already approved for use and others in late-stage clinical trials ( 3). In this time, there has been an unprecedented global effort to identify new diagnostic tests, treatments, and, more recently, vaccines against the virus and the associated disease, COVID-19. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has swept the globe at an alarming rate, with a reported 90 million cases and 1.9 million deaths by the 1-year anniversary of the first death from this pandemic ( 1) and increasing to 119 million cumulative cases and >2.6 million deaths by the middle of March 2021 ( 2). The candidate reference materials assessed did not generate uniform results across several methods, and further steps are needed to enable the harmonization process. The Abbott IgG II anti-SARS-CoV-2 measurement appears to be the first linear method potentially capable of monitoring the immune response to natural infection, including from new emerging variants. The candidate reference materials showed poor correlation across methods, with mixed responses noted in methods that use the spike protein versus the nucleocapsid proteins as their binding antigen. The sensitivity (based on ≥14-day post-positive reverse transcription-PCR samples) and specificity were 98.3% (90.6% to 100.0%) and 99.5% (97.1% to 100%), respectively. The Abbott IgG II method performed well across a wide range of parameters with excellent imprecision (<3.5%) and was linear throughout the positive range (tested to 38,365 AU/ml).

Graphpad prism 4 parameter logistic curve fit verification#

Two different candidate primary reference materials and verification panels were assessed with a goal to move toward harmonization. A comprehensive evaluation of the new Abbott IgG II anti-SARS-CoV-2 IgG method was undertaken using CLSI-based protocols. These should be harmonized to a primary reference material, allowing for the comparison of trial data and improved clinical decision making. To enable meaningful clinical decisions to be made, robustly evaluated, quantitative serology methods are needed. Many were not evaluated rigorously, and there is a significant lack of concordance in results across methods. In the initial stages of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) COVID-19 pandemic, a plethora of new serology tests were developed and introduced to the global market.