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1.
medrxiv; 2022.
Preprint Dans Anglais | medRxiv | ID: ppzbmed-10.1101.2022.10.10.22280850

Résumé

Cancer patients are at high risk of severe COVID-19 with high morbidity and mortality. Further, impaired humoral response renders SARS-CoV-2 vaccines less effective and treatment options are scarce. Randomized trials using convalescent plasma are missing for high-risk patients. Here, we performed a multicenter trial (https://www.clinicaltrialsregister.eu/ctr-search/trial/2020-001632-10/DE) in hospitalized patients with severe COVID-19 within four risk groups (1, cancer; 2, immunosuppression; 3, lab-based risk factors; 4, advanced age) randomized to standard of care (CONTROL) or standard of care plus convalescent/vaccinated anti-SARS-CoV-2 plasma (PLASMA). For the four groups combined, PLASMA did not improve clinically compared to CONTROL (HR 1.29; p=0.205). However, cancer patients experienced shortened median time to improvement (HR 2.50, p=0.003) and superior survival in PLASMA vs. CONTROL (HR 0.28; p=0.042). Neutralizing antibody activity increased in PLASMA but not in CONTROL cancer patients (p=0.001). Taken together, convalescent/vaccinated plasma may improve COVID-19 outcome in cancer patients unable to intrinsically generate an adequate immune response.


Sujets)
Tumeurs , COVID-19
3.
medrxiv; 2022.
Preprint Dans Anglais | medRxiv | ID: ppzbmed-10.1101.2022.02.11.22270831

Résumé

BackgroundComprehensive information about the accuracy of antigen rapid diagnostic tests (Ag-RDTs) for SARS-CoV-2 is essential to guide public health decision makers in choosing the best tests and testing policies. In August 2021, we published a systematic review and meta-analysis about the accuracy of Ag-RDTs. We now update this work and analyze the factors influencing test sensitivity in further detail. Methods and findingsWe registered the review on PROSPERO (registration number: CRD42020225140). We systematically searched multiple databases (PubMed, Web of Science Core Collection, medRvix, bioRvix, and FIND) for publications evaluating the accuracy of Ag-RDTs for SARS-CoV-2 until August 31, 2021. Descriptive analyses of all studies were performed, and when more than 4 studies were available, a random-effects meta-analysis was used to estimate pooled sensitivity and specificity with reverse transcription polymerase chain reaction (RT-PCR) testing as a reference. To evaluate factors influencing test sensitivity, we performed 3 different analyses using multivariate mixed-effects meta-regression models. We included 194 studies with 221,878 Ag-RDTs performed. Overall, the pooled estimates of Ag-RDT sensitivity and specificity were 72.0% (95% confidence interval [CI] 69.8 to 74.2) and 98.9% (95% CI 98.6 to 99.1), respectively. When manufacturer instructions were followed, sensitivity increased to 76.4% (95%CI 73.8 to 78.8). Sensitivity was markedly better on samples with lower RT-PCR cycle threshold (Ct) values (sensitivity of 97.9% [95% CI 96.9 to 98.9] and 90.6% [95% CI 88.3 to 93.0] for Ct-values <20 and <25, compared to 54.4% [95% CI 47.3 to 61.5] and 18.7% [95% CI 13.9 to 23.4] for Ct-values [≥]25 and [≥]30) and was estimated to increase by 2.9 percentage points (95% CI 1.7 to 4.0) for every unit decrease in mean Ct-value when adjusting for testing procedure and patients symptom status. Concordantly, we found the mean Ct-value to be lower for true positive (22.2 [95% CI 21.5 to 22.8]) compared to false negative (30.4 [95% CI 29.7 to 31.1]) results. Testing in the first week from symptom onset resulted in substantially higher sensitivity (81.9% [95% CI 77.7 to 85.5]) compared to testing after 1 week (51.8%, 95% CI 41.5 to 61.9). Similarly, sensitivity was higher in symptomatic (76.2% [95% CI 73.3 to 78.9]) compared to asymptomatic (56.8% [95% CI 50.9 to 62.4]) persons. However, both effects were mainly driven by the Ct-value of the sample. With regards to sample type, highest sensitivity was found for nasopharyngeal (NP) and combined NP/oropharyngeal samples (70.8% [95% CI 68.3 to 73.2]), as well as in anterior nasal/mid-turbinate samples (77.3% [95% CI 73.0 to 81.0]). ConclusionAg-RDTs detect most of the individuals infected with SARS-CoV-2, and almost all when high viral loads are present (>90%). With viral load, as estimated by Ct-value, being the most influential factor on their sensitivity, they are especially useful to detect persons with high viral load who are most likely to transmit the virus. To further quantify the effects of other factors influencing test sensitivity, standardization of clinical accuracy studies and access to patient level Ct-values and duration of symptoms are needed.

4.
medrxiv; 2021.
Preprint Dans Anglais | medRxiv | ID: ppzbmed-10.1101.2021.06.15.21258502

Résumé

Virus mutations have the potential to impact the accuracy of diagnostic tests. The SARS-CoV-2 B.1.1.7 lineage is defined by a large number of mutations in the spike gene and four in the nucleocapsid (N) gene. Most commercially available SARS-CoV-2 antigen-detecting rapid tests (Ag-RDTs) target the viral N-protein, encoded by the N-gene. We conducted a manufacturer-independent, prospective diagnostic accuracy study of three SARS-CoV-2 Ag-RDTs that are currently under review by the WHO Emergency Use Listing Procedure (Espline - Fujirebio Inc.; Sure Status - Premier Medical Corporation Private Limited; Mologic - Mologic Ltd.) and report here on an additional sub-analysis regarding the B.1.1.7 lineage. During the study, in Berlin and Heidelberg, Germany, from 20 January to 15 April 2021, B.1.1.7 rapidly became the dominant SARS-CoV-2 lineage at the testing sites and was detected in 220 (62%) of SARS-CoV-2 RT-PCR positive patients. All three Ag-RDTs yielded comparable sensitivities irrespective of an infection with the B.1.1.7 lineage or not. There is only limited data on how N-gene mutations in variants of concern may impact Ag-RDTs. Currently, no major changes to test performance are anticipated. However, test developers and health authorities should assess and monitor the impact of emerging variants on the accuracy of Ag-RDTs.

5.
medrxiv; 2021.
Preprint Dans Anglais | medRxiv | ID: ppzbmed-10.1101.2021.03.17.21253076

Résumé

BackgroundIn 2020, the World Health Organization (WHO) recommended two SARS-CoV-2 lateral flow antigen detecting rapid diagnostics tests (Ag-RDTs), both initially with nasopharyngeal (NP) sample collection. Independent head-to-head studies demonstrated for SARS-CoV-2 Ag-RDTs nasal sampling to be a comparable and reliable alternative for nasopharyngeal (NP) sampling. MethodsWe conducted a head-to-head comparison study of a supervised, self-collected nasal mid-turbinate (NMT) swab and a professional-collected NP swab, using the Panbio Ag-RDT (the second WHO-listed SARS-CoV-2 Ag-RDT, distributed by Abbott). We calculated positive and negative percent agreement and, compared to the reference standard reverse transcription polymerase chain reaction (RT-PCR), sensitivity and specificity for both sampling techniques. ResultsA SARS-CoV-2 infection could be diagnosed by RT-PCR in 45 of 290 participants (15.5%). Comparing the NMT and NP sampling the positive percent agreement of the Ag-RDT was 88.1% (37/42 PCR positives detected; CI 75.0% - 94.8%). The negative percent agreement was 98.8% (245/248; CI 96.5% - 99.6%). The overall sensitivity of Panbio with NMT sampling was 84.4% (38/45; CI 71.2% - 92.3%) and 88.9% (40/45; CI 76.5% - 95.5%) with NP sampling. Specificity was 99.2% (243/245; CI 97.1% - 99.8%) for both, NP and NMT sampling. The sensitivity of the Panbio test in participants with high viral load (> 7 log10 SARS-CoV-2 RNA copies/mL) was 96.3% (CI 81.7% - 99.8%) for both, NMT and NP sampling. ConclusionFor the Panbio Ag-RDT supervised NMT self-sampling yields to results comparable to NP sampling. This suggests that nasal self-sampling could be used for scale-up population testing.


Sujets)
COVID-19
6.
medrxiv; 2021.
Preprint Dans Anglais | medRxiv | ID: ppzbmed-10.1101.2021.03.15.21253267

Résumé

BackgroundAfter infection with severe acute respiratory syndrome coronavirus (SARS-CoV-2), Immunoglobulin G (IgG) antibodies and virus-specific neutralizing antibodies (nAbs) develop. This study describes antibody responses in a cohort of recovered COVID-19 patients to identify predictors. MethodsWe recruited patients with confirmed SARS-CoV-2 infection from Heidelberg, Germany. Blood samples were collected three weeks after COVID-19 symptoms ended. Participants with high antibody titers were invited for follow-up visits. IgG titers were measured by the Euroimmun Assay, and nAbs titers in a SARS-CoV-2 infection-based assay. Results281 participants were enrolled between April and August 2020 with IgG testing, 145 (51.6%) had nAbs, and 35 (12.5%) had follow-up. The median IgG optical density (OD) ratio was 3.1 (Interquartile range (IQR) 1.6-5.1), and 24.1% (35/145) had a nAb titer>1:80. Higher IgG titers were associated with increased age and more severe disease, and higher nAbs were associated with male gender and CT-value of 25-30 on RT-PCR at diagnosis. The median IgG OD ratio on follow-up was 3.7 (IQR 2.9-5.9), a median increase of 0.5 (IQR -0.3-1.7). Six participants with follow-up nAbs all had titers [≤] 1:80. ConclusionsWhile age and disease severity were correlated with IgG responses, predictive factors for nAbs in convalescent patients remain unclear.


Sujets)
COVID-19 , Syndrome respiratoire aigu sévère
7.
medrxiv; 2021.
Preprint Dans Anglais | medRxiv | ID: ppzbmed-10.1101.2021.03.02.21252430

Résumé

BackgroundRapid antigen-detecting tests (Ag-RDTs) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can transform pandemic control. Thus far, sensitivity ([≤]85%) of lateral-flow assays has limited scale-up. Conceivably, microfluidic immunofluorescence Ag-RDTs could increase sensitivity for SARS-CoV-2 detection. Materials and MethodsThis multi-centre diagnostic accuracy study investigated performance of the microfluidic immunofluorescence LumiraDx assay, enrolling symptomatic and asymptomatic participants with suspected SARS-CoV-2 infection. Participants collected a supervised nasal mid-turbinate (NMT) self-swab for Ag-RDT testing, in addition to a professionally-collected nasopharyngeal (NP) swab for routine testing with reverse transcriptase polymerase chain reaction (RT-PCR). Results were compared to calculate sensitivity and specificity. Sub-analyses investigated the results by viral load, symptom presence and duration. An analytical study assessed exclusivity and limit-of-detection (LOD). In addition, we evaluated ease-of-use. ResultsStudy conduct was between November 2nd 2020 and January 21st 2021. 761 participants were enrolled, with 486 participants reporting symptoms on testing day. 120 out of 146 RT-PCR positive cases were detected positive by LumiraDx, resulting in a sensitivity of 82.2% (95% CI: 75.2%-87.5%). Specificity was 99.3% (CI: 98.3-99.7%). Sensitivity was increased in individuals with viral load [≥] 7 log10 SARS-CoV2 RNA copies/ml (93.8%; CI: 86.2%-97.3%). Testing against common respiratory commensals and pathogens showed no cross-reactivity and LOD was estimated to be 2-56 PFU/mL. The ease-of-use-assessment was favourable for lower throughput settings. ConclusionThe LumiraDx assay showed excellent analytical sensitivity, exclusivity and clinical specificity with good clinical sensitivity using supervised NMT self-sampling.


Sujets)
COVID-19
8.
medrxiv; 2021.
Preprint Dans Anglais | medRxiv | ID: ppzbmed-10.1101.2021.02.26.21252546

Résumé

ABSTRACT Background SARS-CoV-2 antigen rapid diagnostic tests (Ag-RDTs) are increasingly being integrated in testing strategies around the world. Studies of the Ag-RDTs have shown variable performance. In this systematic review and meta-analysis, we assessed the clinical accuracy (sensitivity and specificity) of commercially available Ag-RDTs. Methods and Results We registered the review on PROSPERO (Registration number: CRD42020225140). We systematically searched multiple databases (PubMed, Web of Science Core Collection, medRvix and bioRvix, FIND) for publications evaluating the accuracy of Ag-RDTs for SARS-CoV-2 up until April 30 th , 2021. Descriptive analyses of all studies were performed and when more than four studies were available, a random-effects meta-analysis was used to estimate pooled sensitivity and specificity in comparison to reverse transcriptase polymerase chain reaction testing. We assessed heterogeneity by subgroup analyses, and rated study quality and risk of bias using the QUADAS 2 assessment tool. From a total of 14,254 articles, we included 133 analytical and clinical studies resulting in 214 clinical accuracy data sets with 112,323 samples. Across all meta-analyzed samples, the pooled Ag-RDT sensitivity was 71.2% (95% confidence interval [CI] 68.2 to 74.0) and increased to 76.3% (CI 73.1 to 79.2) if analysis was restricted to studies that followed the Ag-RDT manufacturers’ instructions. The LumiraDx showed the highest sensitivity with 88.2% (CI 59.0 to 97.5). Of instrument-free Ag-RDTs, Standard Q nasal performed best with 80.2% sensitivity (CI 70.3 to 87.4). Across all Ag-RDTs sensitivity was markedly better on samples with lower Ct-values, i.e., <20 (96.5%, CI 92.6 to 98.4) and <25 (95.8%, CI 92.3 to 97.8), in comparison to those with Ct ≥25 (50.7%, CI 35.6 to 65.8) and ≥30 (20.9%, CI 12.5 to 32.8). Testing in the first week from symptom onset resulted in substantially higher sensitivity (83.8%, CI 76.3 to 89.2) compared to testing after one week (61.5%, CI 52.2 to 70.0). The best Ag-RDT sensitivity was found with anterior nasal sampling (75.5%, CI 70.4 to 79.9) in comparison to other sample types (e.g., nasopharyngeal 71.6%, CI 68.1 to 74.9) although CIs were overlapping. Concerns of bias were raised across all data sets, and financial support from the manufacturer was reported in 24.1% of data sets. Our analysis was limited by the included studies’ heterogeneity in design and reporting, making it difficult to draw conclusions from. Conclusion In this study we found that Ag-RDTs detect the vast majority of cases within the first week of symptom onset and those with high viral load. Thus, they can have high utility for diagnostic purposes in the early phase of disease, making them a valuable tool to fight the spread of SARS-CoV-2. Standardization in conduct and reporting of clinical accuracy studies would improve comparability and use of data. AUTHOR SUMMARY Why was this study done? – Antigen rapid diagnostic tests (Ag-RDTs) are considered an important diagnostic tool to fight the spread of SARS-CoV-2 – An increasing number of Ag-RDTs is offered on the market, and a constantly growing body of literature evaluating their performance is available – To inform decision makers about the best test to choose, an up to date summary of their performance is needed What did the researchers do and find? – On a weekly basis, we search multiple data bases for evaluations of Ag-RDTs detecting SARS-CoV-2 and post the results on www.diagnosticsglobalhealth.org – Based on the search results up until April 30 th , 2021, we conducted a systematic review and meta-analysis, including a total of 133 clinical and analytical accuracy studies – Across all meta-analyzed studies, when Ag-RDTs were performed according to manufacturers’ recommendations, they showed a sensitivity of 76.3% (CI 73.1 to 79.2), with the LumiraDx (sensitivity 88.2%, CI 59.0 to 97.5) and of the instrument-free Ag-RDT Standard Q (74.9% sensitivity, CI 69.3 to 79.7) performing best. – Across all Ag-RDTs, sensitivity increased to 95.8% (CI 92.3 to 97.8) when restricting the analysis to samples with high viral loads (i.e., a Ct-value <25) and to 83.8% (CI 76.3 to 89.2) when tests were performed on patients within the first week after symptom onset What do these findings mean? – Ag-RDTs detect the vast majority of cases within the first week of symptom onset and those with high viral load. Thus, they can have high utility for diagnostic purposes in the early phase of disease – Out of all assessed tests, the Lumira Dx showed the highest accuracy. The Standard Q wasthe best performing test when only considering those that don’t require an instrument – A standardization of reporting methods for clinical accuracy studies would enhance future test-comparisons

9.
medrxiv; 2021.
Preprint Dans Anglais | medRxiv | ID: ppzbmed-10.1101.2021.01.06.20249009

Résumé

Background Antigen-detecting rapid diagnostic tests (Ag-RDTs) have been widely recommended as a complement to RT-PCR. Considering the possibility of nasal self-sampling and the ease-of-use in performing the test, self-testing may be an option. Methods and Findings We performed a manufacturer-independent, prospective diagnostic accuracy study of nasal mid-turbinate self-sampling and self-testing when using a WHO-listed SARS-CoV-2 Ag-RDT. Symptomatic participants suspected to have COVID-19 received written and illustrated instructions. Procedures were observed without intervention. For comparison, Ag-RDTs with nasopharyngeal sampling were professionally performed. Estimates of agreement, sensitivity, and specificity relative to RT-PCR on a combined oro-/nasopharyngeal sample were calculated. Feasibility was evaluated by observer and participant questionnaires. Among 146 symptomatic adults, 40 (27.4%) were RT-PCR-positive for SARS-CoV-2. Sensitivity with self-testing was 82.5% (33/40 RT-PCR positives detected; 95% CI 68.1-91.3), and 85.0% (34/40; 95% CI 70.9-92.9) with professional testing. The positive percent agreement between self-testing and professional testing on Ag-RDT was 91.4% (95% CI 77.6-97.0), and negative percent agreement 99.1% (95% CI 95.0-100). At high viral load (>7.0 log10 SARS-CoV-2 RNA copies/ml), sensitivity was 96.6% (28/29; 95% CI 82.8-99.8) for both self- and professional testing. Deviations in sampling and testing (incomplete self-sampling or extraction procedure, or imprecise volume applied on the test device) were observed in 25 out of the 40 PCR-positives. Participants were rather young (mean age 35 years) and educated (59.6% with higher education degree). Most participants (80.9%) considered the Ag-RDT as rather easy to perform. Conclusion Ambulatory participants suspected for SARS-CoV-2 infection were able to reliably perform the Ag-RDT and test themselves. Procedural errors might be reduced by refinement of the Ag-RDTs for self-testing, such as modified instructions for use or product design/procedures. Self-testing may result in more wide-spread and more frequent testing. Paired with the appropriate information and education of the general public about the benefits and risks, self-testing may therefore have significant impact on the pandemic.


Sujets)
COVID-19
10.
medrxiv; 2020.
Preprint Dans Anglais | medRxiv | ID: ppzbmed-10.1101.2020.12.03.20243725

Résumé

BackgroundNasopharyngeal (NP) swab samples for antigen-detecting rapid diagnostic tests (Ag-RDTs) require qualified healthcare professionals and are frequently perceived as uncomfortable by patients. MethodsWe performed a manufacturer-independent, prospective diagnostic accuracy study, comparing professional-collected nasal mid-turbinate (NMT) to nasopharyngeal swab, using the test kits of a WHO-listed SARS-CoV-2 Ag-RDT (STANDARD Q COVID-19 Ag Test, SD Biosensor), which is also being distributed by Roche. Individuals with high suspicion for COVID-19 infection were tested. The reference standard was RT-PCR using a combined oro-/nasopharyngeal swab sample. Percent positive and negative agreement, as well as sensitivity and specificity were calculated. ResultsAmong the 179 participants, 41 (22.9%) tested positive for SARS-CoV-2 by RT-PCR. The positive percent agreement of the two different sampling techniques for the Ag-RDT was 93.5% (CI 79.3-98.2). The negative percent agreement was 95.9% (CI 91.4-98.1). The Ag-RDT with NMT-sampling showed a sensitivity of 80.5% (33/41 PCR positives detected; CI 66.0-89.8) and specificity of 98.6% (CI 94.9-99.6) compared to RT-PCR. The sensitivity with NP-sampling was 73.2% (30/41 PCR positives detected; CI 58.1-84.3) and specificity was 99.3% (CI 96.0-100). In patients with high viral load (>7.0 log10 SARS-CoV-2 RNA copies/swab), the sensitivity of the Ag-RDT with NMT-sampling was 100% and 94.7% with NP-sampling. ConclusionThis study demonstrates that sensitivity of a WHO-listed SARS-CoV-2 Ag-RDT using a professional nasal-sampling kit is at least equal to that of the NP-sampling kit, although confidence intervals overlap. Of note, differences in the IFUs of the test procedures could have contributed to different sensitivities. NMT-sampling can be performed with less training, reduces patient discomfort, and it enables scaling of antigen testing strategies. Additional studies of patient self-sampling should be considered to further facilitate the scaling-up of Ag-RDT testing.


Sujets)
COVID-19
11.
medrxiv; 2020.
Preprint Dans Anglais | medRxiv | ID: ppzbmed-10.1101.2020.11.27.20239699

Résumé

BackgroundDiagnostics are essential for controlling the pandemic. Identifying a reliable and fast diagnostic is needed to support testing. We assessed performance and ease-of-use of the Abbott PanBio antigen-detecting rapid diagnostic test (Ag-RDT). MethodsThis prospective, multi-centre diagnostic accuracy study enrolled at two sites in Germany. Following routine testing with RT-PCR, a second study-exclusive swab was performed for Ag-RDT testing. Routine swabs were nasopharyngeal (NP) or combined NP/oropharyngeal (OP) whereas the study-exclusive swabs were NP. To evaluate performance, sensitivity and specificity were assessed overall and in predefined sub analyses accordingly to cycle-threshold values, days of symptoms, disease severity and study site. Additionally, an ease-of-use assessment and System Usability Scale (SUS) were performed. Findings1108 participants were enrolled between Sept 28 and Oct 30, 2020. Of these, 106 (9{middle dot}6%) were PCR-positive. The Abbott PanBio detected 92/106 PCR-positive participants with a sensitivity of 86{middle dot}8% (95% CI: 79{middle dot}0% - 92{middle dot}0%) and a specificity of 99{middle dot}9% (95% CI: 99{middle dot}4%-100%). The sub analyses indicated that sensitivity was 95{middle dot}8% in CT-values <25 and within the first seven days from symptom onset. The test was characterized as easy to use (SUS: 86/100) and considered suitable for point-of- care settings. InterpretationThe Abbott PanBio Ag-RDT performs well for SARS-CoV-2 testing in this large manufacturer independent study, confirming its WHO recommendation for Emergency Use in settings with limited resources. FundingThe Foundation of Innovative New Diagnostics supplied the test kits for the study. The internal funds from the Heidelberg University as well as the Charite Berlin supported this study.

12.
medrxiv; 2020.
Preprint Dans Anglais | medRxiv | ID: ppzbmed-10.1101.2020.10.26.20219600

Résumé

BackgroundTwo antigen-detecting rapid diagnostic tests (Ag-RDTs) are now approved through the WHO Emergency Use Listing procedure and can be performed at the point-of-care. However, both tests use nasopharyngeal (NP) swab samples. NP swab samples must be collected by trained healthcare personnel with protective equipment and are frequently perceived as uncomfortable by patients. MethodsThis was a manufacturer-independent, prospective diagnostic accuracy study with comparison of a supervised, self-collected anterior nose (AN) swab sample with a professional-collected NP swab sample, using a WHO-listed SARS-CoV-2 Ag-RDT, STANDARD Q COVID-19 Ag Test (SD Biosensor), which is also being distributed by Roche. The reference standard was RT-PCR from an oro-/nasopharyngeal swab sample. Percent positive and negative agreement as well as sensitivity and specificity were calculated. ResultsAmong the 289 participants, 39 (13.5%) tested positive for SARS-CoV-2 by RT-PCR. The positive percent agreement of the two different sampling techniques for the Ag-RDT was 90.6% (CI 75.8-96.8). The negative percent agreement was 99.2% (CI 97.2-99.8). The Ag-RDT with AN sampling showed a sensitivity of 74.4% (29/39 PCR positives detected; CI 58.9-85.4) and specificity of 99.2% (CI 97.1-99.8) compared to RT-PCR. The sensitivity with NP sampling was 79.5% (31/39 PCR positives detected; CI 64.5-89.2) and specificity was 99.6% (CI 97.8-100). In patients with high viral load (>7.0 log 10 RNA SARS-CoV2/swab), the sensitivity of the Ag-RDT with AN sampling was 96% and 100% with NP sampling. ConclusionSupervised self-sampling from the anterior nose is a reliable alternative to professional nasopharyngeal sampling using a WHO-listed SARS-CoV-2 Ag-RDT. Considering the ease-of-use of Ag-RDTs, self-sampling and potentially patient self-testing at home may be a future use case.


Sujets)
COVID-19
13.
medrxiv; 2020.
Preprint Dans Anglais | medRxiv | ID: ppzbmed-10.1101.2020.10.01.20203836

Résumé

Abstract Background: Reliable point-of-care (POC) diagnostics not requiring laboratory infrastructure could be a game changer in the COVID-19 pandemic, particularly in the Global South. We assessed performance, limit of detection (LOD) and ease-of-use of three antigen-detecting, rapid POC diagnostics (Ag-RDT) for SARS-CoV-2. Methods: This prospective, multi-centre diagnostic accuracy study, recruited participants suspected to have SARS-CoV2 in Germany and UK. Paired nasopharyngeal swabs (NP) or NP and/or oropharyngeal swabs (OP) were collected from participants (one for clinical real-time reverse transcription polymerase chain reaction (RT-PCR) and one for Ag-RDT testing). Performance of each of three Ag-RDTs was compared to RT-PCR overall, and according to predefined subcategories e.g. cycle threshold (CT)-value, days from symptom onset, etc. In addition, limited verification of analytical limit-of-detection (LOD) was determined. To understand the usability of each Ag-RDT a System Usability Scale (SUS) questionnaire and ease-of-use assessment were performed. Results: Between April 17th and August 25th, 2020, 2417 participants were enrolled, with 70 (3.0%) testing positive by RT-PCR. The best-performing test (SD Biosensor, Inc. STANDARD Q) was 76.6% [95% Confidence Interval (CI) 62.8-86.4] sensitive and 99.3% [CI 98.6-99.6] specific. A sub-analysis showed all samples with RT-PCR CT-values <25 were detectable by STANDARD Q. The test was considered easy-to-use (SUS 86/100) and suitable for POC. Bioeasy and Coris showed specificity of 93.1% [CI 91.0%-94.8%] and 95.8% [CI 93.4%-97.4%], respectively, not meeting the predefined target of [≥]98%. Conclusion: There is large variability in performance of Ag-RDT tests with one test showing promise. Given the usability at POC, these tests are likely to have impact despite imperfect sensitivity; however further research and modelling are needed.


Sujets)
COVID-19
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