Result for
Tag: testing
September 28, 2020
Mass Screening of Asymptomatic Persons for SARS-CoV-2 Using Saliva
A study that conducted mass screening for SARS-CoV-2 among two cohorts of asymptomatic persons in Japan, a contact tracing cohort (n=161) and an airport quarantine cohort (n=1,763), reported the overall sensitivity of RT-PCR testing with nasopharyngeal (NP) swabs was 86% and saliva samples was 92%, with specificity for both samples >99.9%. Due to the lack…
Humoral Response and PCR Positivity in Patients with COVID-19 in the New York City Region, USA: An Observational Study
A cross-sectional study in the New York City region reported that 99.5% patients with PCR-confirmed SARS-CoV-2 infection (n=624) and 37% patients with suspected SARS-CoV-2 infection (n=719) showed evidence of seroconversion with anti-SARS-CoV-2 spike antibodies detected 4 weeks after the illness. PCR positivity was detected up to 28 days from symptom resolution. Wajnberg et al. (Sept…
September 25, 2020
Comparative assessment of multiple COVID-19 serological technologies supports continued evaluation of point-of-care lateral flow assays in hospital and community healthcare settings
[Pre-print, not peer reviewed] A comparison of ten commercial serological tests for SARS-CoV-2 antibodies found sensitivity ranging from 61% to 87% and specificity ranging from 82% to 100% when compared to an in-house ELISA. The in-house test was selected as the reference test because there is no accepted “gold standard” for the detection of SARS-CoV2…
Sensitive detection of SARS-CoV-2-specific-antibodies in dried blood spot samples
[Pre-print, not peer reviewed] Dried blood spot (DBS) sampling was validated for detection of SARS-CoV-2-specific antibodies. DBS sampling achieved a sensitivity of 98.1% and specificity of 100% for detecting anti-spike glycoprotein antibodies based on samples from 87 matched DBS and serum samples obtained from eighty individuals. Morley et al. (Sept 25, 2020). Sensitive detection of…
Assessment of Disparities in COVID-19 Testing and Infection Across Language Groups in Seattle, Washington
Out of a patient population of 562,242 in King County, WA, a slightly lower percentage of non-English speakers had been tested for SARS-CoV-2 compared to English-speakers (5% vs 6%), but the proportion of positive tests was 4.6-fold higher among non-English speakers (19% vs 4%). The elevated proportion of positive tests was observed across multiple languages….
September 24, 2020
Massive and Rapid COVID-19 Testing Is Feasible by Extraction-Free SARS-CoV-2 RT-PCR
Smyrlaki et al. developed a streamlined protocol for SARS-CoV-2 testing using RT-PCR directly on heat-inactivated samples and lysates without the need for RNA extraction, which is a bottleneck in PCR testing. Their protocol achieved a sensitivity of 96% and specificity of 99.8% compared to conventional RT-PCR. The authors suggest that this novel protocol could have…
Utility of Repeat Nasopharyngeal SARS-CoV-2 RT-PCR Testing and Refinement of Diagnostic Stewardship Strategies at a Tertiary Care Academic Center in a Low-Prevalence Area of the United States
Among 660 patients with at least 2 nasopharyngeal SARS-CoV-2 PCR tests collected on different days in a low prevalence area of Wisconsin, only 6 (0.9%) negative-to-positive conversions were detected. All 6 were outpatient persons under investigation (PUI) for suspected COVID-19. Overall, 29.6% of repeat PUI testing and 31.4% of repeat asymptomatic screens should not have…
Performance Characteristics of Five Immunoassays for SARS-CoV-2: A Head-to-Head Benchmark Comparison
Four commercial and widely available SARS-CoV-2 IgG assays (Abott, DiaSorine, Roche, and Siemens), and a novel immunoassay (Oxford) were evaluated for performance using identical sample sets. All assays achieved a sensitivity ≥98% and specificity≥98% on samples taken 30 days or more post-symptom onset, based on 976 pre-pandemic blood samples collected in 2014-2016 and 536 blood…
September 23, 2020
Evaluation of Pooled Sample Analysis Strategy in Expediting Case Detection in Areas with Emerging Outbreaks of COVID-19: A Pilot Study
Pooling 5 nasopharyngeal or oropharyngeal samples during PCR testing would offer a reduction of laboratory turn-around time by 66% and the cost of diagnosis by 68%. However, the sensitivity was compromised, with 5 of the 109 pools showing discordant results when compared with individual results. Single samples with Ct value ³34 were likely to be…
September 22, 2020
Kinetics of SARS-CoV-2 Specific Antibodies (IgM, IgA, IgG) in Non-Hospitalized Patients Four Months Following Infection
Levels of antibodies against SARS-CoV-2 were found to decline over an 18-week period following symptom onset, although antibodies remained detectable. Data from longitudinal profiles of different antibody immunoglobulin classes using tests with different antigens and neutralizing titers showed that receptor-binding-domain-specific (RBD) and nucleocapsid protein-specific (NCP) IgM as well as S1-specific IgA levels significantly decreased within…
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