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1.
Lab Med ; 52(5): e137-e146, 2021 Sep 01.
Article in English | MEDLINE | ID: covidwho-1387950

ABSTRACT

OBJECTIVE: To describe a cross-institutional approach to verify the Abbott ARCHITECT SARS-CoV-2 antibody assay and to document the kinetics of the serological response. METHODS: We conducted analytical performance evaluation studies using the Abbott ARCHITECT SARS-CoV-2 antibody assay on 5 Abbott ARCHITECT i2000 automated analyzers at 2 academic medical centers. RESULTS: Within-run and between-run coefficients of variance (CVs) for the antibody assay did not exceed 5.6% and 8.6%, respectively, for each institution. Quantitative and qualitative results agreed for lithium heparin plasma, EDTA-plasma and serum specimen types. Results for all SARS-CoV-2 IgG-positive and -negative specimens were concordant among analyzers except for 1 specimen at 1 institution. Qualitative and quantitative agreement was observed for specimens exchanged between institutions. All patients had detectable antibodies by day 10 from symptom onset and maintained seropositivity throughout specimen procurement. CONCLUSIONS: The analytical performance characteristics of the Abbott ARCHITECT SARS-CoV-2 antibody assay within and between 2 academic medical center clinical laboratories were acceptable for widespread clinical-laboratory use.


Subject(s)
Antibodies, Viral/blood , COVID-19 Serological Testing/standards , COVID-19/diagnosis , Immunoassay/standards , Immunoglobulin G/blood , SARS-CoV-2/immunology , Academic Medical Centers , COVID-19/blood , COVID-19/immunology , COVID-19/virology , Humans , Observer Variation , Reproducibility of Results , SARS-CoV-2/pathogenicity , Sensitivity and Specificity , Virginia
2.
Int Arch Allergy Immunol ; 182(5): 417-424, 2021.
Article in English | MEDLINE | ID: covidwho-1097047

ABSTRACT

BACKGROUND: Detailed understanding of the immune response to severe acute respiratory syndrome coronavirus (SARS-CoV)-2, the cause of coronavirus disease 2019 (CO-VID-19) has been hampered by a lack of quantitative antibody assays. OBJECTIVE: The objective was to develop a quantitative assay for IgG to SARS-CoV-2 proteins that could be implemented in clinical and research laboratories. METHODS: The biotin-streptavidin technique was used to conjugate SARS-CoV-2 spike receptor-binding domain (RBD) or nucleocapsid protein to the solid phase of the ImmunoCAP. Plasma and serum samples from patients hospitalized with COVID-19 (n = 60) and samples from donors banked before the emergence of COVID-19 (n = 109) were used in the assay. SARS-CoV-2 IgG levels were followed longitudinally in a subset of samples and were related to total IgG and IgG to reference antigens using an ImmunoCAP 250 platform. RESULTS: At a cutoff of 2.5 µg/mL, the assay demonstrated sensitivity and specificity exceeding 95% for IgG to both SARS-CoV-2 proteins. Among 36 patients evaluated in a post-hospital follow-up clinic, median levels of IgG to spike-RBD and nucleocapsid were 34.7 µg/mL (IQR 18-52) and 24.5 µg/mL (IQR 9-59), respectively. Among 17 patients with longitudinal samples, there was a wide variation in the magnitude of IgG responses, but generally the response to spike-RBD and to nucleocapsid occurred in parallel, with peak levels approaching 100 µg/mL, or 1% of total IgG. CONCLUSIONS: We have described a quantitative assay to measure IgG to SARS-CoV-2 that could be used in clinical and research laboratories and implemented at scale. The assay can easily be adapted to measure IgG to mutated COVID-19 proteins, has good performance characteristics, and has a readout in standardized units.


Subject(s)
Antibodies, Viral/blood , COVID-19 Serological Testing/methods , COVID-19/diagnosis , COVID-19/immunology , Immunoglobulin G/blood , SARS-CoV-2/immunology , Biomarkers/blood , COVID-19/virology , Humans , Longitudinal Studies , Sensitivity and Specificity
3.
Open Forum Infect Dis ; 7(10): ofaa406, 2020 Oct.
Article in English | MEDLINE | ID: covidwho-873050

ABSTRACT

BACKGROUND: The novel severe acute respiratory coronavirus 2 (SARS-CoV-2) that causes coronavirus disease 2019 (COVID-19) originated in December 2019 and has now infected almost 5 million people in the United States. In the spring of 2020, private laboratories and some hospitals began antibody testing despite limited evidence-based guidance. METHODS: We conducted a retrospective chart review of patients who received SARS-CoV-2 antibody testing from May 14, 2020, to June 15, 2020, at a large academic medical center, 1 of the first in the United States to provide antibody testing capability to individual clinicians in order to identify clinician-described indications for antibody testing compared with current expert-based guidance from the Infectious Diseases Society of America (IDSA) and the Centers for Disease Control and Prevention (CDC). RESULTS: Of 444 individual antibody test results, the 2 most commonly described testing indications, apart from public health epidemiology studies (n = 223), were for patients with a now resolved COVID-19-compatible illness (n = 105) with no previous molecular testing and for asymptomatic patients believed to have had a past exposure to a person with COVID-19-compatible illness (n = 60). The rate of positive SARS-CoV-2 antibody testing among those indications consistent with current IDSA and CDC guidance was 17% compared with 5% (P < .0001) among those indications inconsistent with such guidance. Testing inconsistent with current expert-based guidance accounted for almost half of testing costs. CONCLUSIONS: Our findings demonstrate a dissociation between clinician-described indications for testing and expert-based guidance and a significantly different rate of positive testing between these 2 groups. Clinical curiosity and patient preference appear to have played a significant role in testing decisions and substantially contributed to testing costs.

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