Distinct characteristics of COVID-19 patients with initial rRT-PCR-positive and rRT-PCR-negative results for SARS-CoV-2.
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ABSTRACT:
SUBMITTER: Zhang JJ
PROVIDER: S-EPMC7262033 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:IntroductionThe gold standard for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection is real-time reverse transcription PCR (rRT-PCR), which is expensive, has a long turnaround time and requires special equipment and trained personnel. Nasopharyngeal swabs are uncomfortable, not suitable for certain patient groups and do not allow self-testing. Convenient, well-tolerated rapid antigen tests (RATs) for SARS-CoV-2 detection are called for.Gap statementMore real-life performance data on anterior nasal RATs are required.AimWe set out to evaluate the anterior nasal AMP RAT in comparison with rRT-PCR in a hospital cohort.MethodologyThe study included 175 patients, either hospitalized in a coronavirus disease 2019 (COVID-19) ward or screened in a preadmittance outpatient clinic. Two swabs were collected per patient: an anterior nasal one for the RAT and a combined naso-/oropharyngeal one for the rRT-PCR. Sixty-five patients (37%) were rRT-PCR-positive [cycle threshold (C t) <40].ResultsThe anterior nasal AMP RAT showed an overall sensitivity and specificity of 29.2 % (18.6-41.8, 95 % CI) and 100.0 % (96.7-100.0, 95 % CI) respectively. In patients with a C t value <25, <30 and <33, higher sensitivities were observed. Time since symptom onset was significantly higher in patients with a false-negative RAT (P=0.02).ConclusionThe anterior nasal AMP RAT showed low sensitivities in this cohort, especially in patients with a longer time since symptom onset. Further knowledge concerning the viral load and antigen expression over time and in different swabbing locations is needed to outline the usage time frame for SARS-CoV-2 RAT.
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Project description:This study used digital polymerase chain reaction (dPCR) to determine whether envelope (E) gene-negative and nucleocapsid (N2) gene-positive (E-N+) results obtained with the Cepheid Xpert Xpress SARS-CoV-2 assay are reliable. Using droplet digital PCR results as a reference, 18 of 22 E-N+ samples with a low viral load (81.8%) were identified as true positives.
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