In-Depth Longitudinal Comparison of Clinical Specimens to Detect SARS-CoV-2

The testing and isolation of patients with coronavirus disease 2019 (COVID-19) are indispensable tools to control the ongoing COVID-19 pandemic. PCR tests are considered the “gold standard” of COVID-19 testing and mostly involve testing nasopharyngeal swab specimens. Our study aimed to compare the sensitivity of tests for various sample specimens. Seventy-five participants with confirmed COVID-19 were included in the study. Nasopharyngeal swabs, oropharyngeal swabs, Oracol-collected saliva, throat washes and rectal specimens were collected along with pooled swabs. Participants were asked to complete a questionnaire to correlate specific clinical symptoms and the symptom duration with the sensitivity of detecting COVID-19 in various sample specimens. Sampling was repeated after 7 to 10 days (T2), then after 14 to 20 days (T3) to perform a longitudinal analysis of sample specimen sensitivity. At the first time point, the highest percentages of SARS-CoV-2-positive samples were observed for nasopharyngeal samples (84.3%), while 74%, 68.2%, 58.8% and 3.5% of throat washing, Oracol-collected saliva, oropharyngeal and rectal samples tested positive, respectively. The sensitivity of all sampling methods except throat wash samples decreased rapidly at later time points compared to the first collection. The throat washing method exhibited better performance than the gold standard nasopharyngeal swab at the second and third time points after the first positive test date. Nasopharyngeal swabs were the most sensitive specimens for early detection after symptom onset. Throat washing is a sensitive alternative method. It was found that SARS-CoV-2 persists longer in the throat and saliva than in the nasopharynx.

Limits and Opportunities of SARS-CoV-2 Antigen Rapid Tests: An Experienced-Based Perspective

Background: Due to the steadily rising case numbers of SARS-CoV-2 infections worldwide, there is an increasing need for reliable rapid diagnostic devices in addition to existing gold standard PCR methods. Actually, public attention is focused on antigen assays including lateral flow tests (LFTs) as a diagnostic alternative. Therefore, different LFTs were analyzed regarding their performance in a clinical setting. Material and Methods: A pilot sample panel of 13 bronchoalveolar fluids (BALFs) and 60 throat washing (TW) samples with confirmed PCR results, as well as eight throat washes invalid by PCR, were tested with the BIOCREDIT test (RapiGEN), the PanbioTM assay (Abbott), and the SARS-CoV-2 rapid antigen test (Roche). Conclusion: The analyzed antigen test showed an interassay correlation of 27.4%, with overall specificities ranging from 19.4% to 87.1%, while sensitivities of the respective tests ranged between 33.3% and 88.1%. Because these assays did not entirely meet all high expectations, their benefit has to be carefully evaluated for the respective test strategy and setting.

Limits and opportunities of SARS-CoV-2 antigen rapid tests – an experience based perspective

BackgroundDue to the steadily rising case numbers of SARS-CoV-2 infections worldwide there is an increasing need for reliable rapid diagnostic devices in addition to existing gold standard PCR-methods. Actually, public attention is focused on antigen assays including lateral flow tests (LFTs) as diagnostic alternative. Therefore, different LFTs were analyzed regarding their performance in a clinical setting.Material and MethodsA pilot sample panel of 13 BALFs and 60 throat washing samples (TWs) with confirmed PCR results as well as 8 throat washes invalid by PCR was tested with the BIOCREDIT test (RapiGEN), the Panbio™ assay (Abbott), and the SARS-CoV-2 Rapid Antigen Test (Roche).ConclusionThe analyzed antigen test showed an inter-assay correlation of 27.4% with overall specificities ranging from 19.4% to 87.1%, while sensitivities of the respective tests ranged between 33.3% and 88.1%. Although these assays did not entirely meet all high expectations their benefit has to be carefully evaluated for the respective test strategy and setting.

Effect of Throat Washings on Detection of 2019 Novel Coronavirus

The 2019 novel coronavirus was detected in self-collected throat washings. The positive testing rate of throat washing was much higher than that of nasopharyngeal swabs. Throat washing is a promising candidate for 2019-nCoV screening and monitoring due to its noninvasiveness and reliability.