Result for
Tag: testing
November 18, 2020
Clinical Performances of Three Fully Automated Anti-SARS-CoV-2 Immunoassays Targeting the Nucleocapsid or Spike Proteins
Both commercial spike and nucleocapsid serologic tests have approximately equivalent sensitivity for clinical diagnosis after PCR-confirmed SARS-CoV-2 infection. A study of 137 samples from 96 patients evaluating three commercial anti‐SARS‐CoV‐2 antibody assays for the detection of COVID-19 reactive antibodies reported equivalent sensitivities (range 70.4%-85.2%) within 14 days from symptom onset to PCR-confirmed diagnosis. At 28…
November 16, 2020
SARS-CoV-2 Serological Tests Can Generate False Positive Results for Samples from Patients with Chronic Inflammatory Diseases
[Pre-print, not peer-reviewed] Most SARS-CoV-2 serological assays were sensitive to interfering antibodies in samples from patients with chronic inflammatory diseases, which may lead to false positivity. Samples from patients with multiple sclerosis (MS), rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) were evaluated with 17 commercially-available lateral flow assays. Six of those assays, plus an…
November 13, 2020
Assessment of SARS-CoV-2 RNA Test Results Among Patients Who Recovered From COVID-19 With Prior Negative Results
A prospective study of 176 Italians who had recovered from COVID-19 and previously tested negative for SARS-CoV-2 RNA via RT-PCR (two negative tests 24 hours apart) found that 32 people (18%) re-tested positive for SARS-CoV-2 (mean of 49 days since initial diagnosis), and one person (3%) was found to have replicative SARS-CoV-2 RNA. It was…
Comparison of SARS-COV-2 Nasal Antigen Test to Nasopharyngeal RT-PCR in Mildly Symptomatic Patients
[Pre-print, not peer-reviewed] A study evaluating the diagnostic performance of a rapid antigen detection test (RADT) indicated that the sensitivity and specificity were 82.1% and 99.1% respectively in patients with mild COVID-19 in a high incidence setting, and the performance was especially high among samples with a high viral load. Nasal samples from male patients…
Validation and Testing of a Method for Detection of SARS-CoV-2 RNA in Healthy Human Stool
[Pre-print, not peer-reviewed] An assay designed to detect SARS-CoV-2 RNA in stool based upon a modified version of the CDC rRT-PCR SARS-CoV-2 test. Using stool samples from health individuals spiked with inactivated SAR-CoV-2 virus, the lower limit of detection (LoD) of the assay was found to be 3,000 viral RNA copies per gram of original…
Performance of Nucleic Acid Amplification Tests for Detection of Severe Acute Respiratory Syndrome Coronavirus 2 in Prospectively Pooled Specimens
A study evaluating the test performance characteristics of 3 nucleic acid amplification tests for SARS-CoV-2 found that the positive percent agreement (PPA) of pooled versus individual testing ranged from 71.7% to 82.6% for pools of 8 and from 82.9% to 100.0% for pools of 4. Pooled samples showed decreased PPA relative to individual samples. False…
November 9, 2020
Differences of SARS-CoV-2 Serological Test Performance between Hospitalized and Outpatient COVID-19 Cases
A study evaluating two commercially available SARS-CoV-2 serological assays (Virotech, VT-assays and Euroimmun, EI-assays) among using 116 COVID-19 cases (51 inpatients and 65 outpatients) reported the sensitivity of the VT-assay against IgA and IgG was markedly lower among outpatients than inpatients (IgA: 6% vs. 64%; IgG: 86% vs. 96%). The sensitivity of the EI-assay against…
November 4, 2020
Association of COVID-19 RT-QPCR Test False-Negative Rate with Patient Age Sex and Time since Diagnosis
[Preprint, not peer-reviewed] A study using electronic health records in Israel reported that the 11% of PCR tests for SARS-CoV-2 were negative with 0-5 days of clinical diagnosis among patients who had at least one positive PCR test (n= 521,696). Patients who were female (vs. male: OR=1.7) and patients who were younger (10 vs. 40…
SARS-CoV-2 Detection by Nasal Strips a Superior Tool for Surveillance of Pediatric Populations
In pediatric patients, the use of small strips inserted into each nostril was shown to have a sensitivity of 94% and specificity of 100% for the detection of SARS-CoV-2 when compared to pooled nasopharyngeal swab and throat swab samples. Viral loads of SARS-CoV-2 RNA were similar between paired nasal strip samples and nasal swab samples….
November 3, 2020
Outcomes of Contact Tracing in San Francisco, California—Test and Trace During Shelter-in-Place
From April 13 to June 8, San Francisco’s contact tracing program was able to reach 85% (1,394 out of 1,633) of reported cases and subsequent contacts and secondary cases for interviews. People who identified as Latino represented a majority of these cases, despite comprising 15% of San Francisco residents. The secondary household attack proportion (percentage…
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