Validation of the Cepheid Xpert® Xpress SARS-CoV-2 using upper and lower respiratory tract specimens
Bibliographic record
Abstract
This study validated the performance of the reverse transcriptase-polymerase chain reaction (rRT-PCR) based Cepheid Xpert® Xpress SARS-CoV-2 assay against the TIB MOLBIOL E-gene/EAV, a standard laboratory rRT-PCR SARS-CoV-2 assay. Upper and lower respiratory tract samples (nasopharyngeal and nasal swabs, bronchoalveolar lavage, and tracheal aspirate) were obtained from patients suspected to have contracted COVID-19. Results from the Xpert® Xpress and standard rRT-PCR assays were compared for positive and negative agreement and analyzed for precision, reproducibility, 95% confidence intervals, and coefficients of variation. The Xpert® Xpress assay demonstrated 100% agreement with the standard lab rRT-PCR for both upper and lower respiratory tract samples. Both the Xpert® Xpress and lab rRT-CPR identified weakly positive (Ct values 35-39) sample replicates with 100% reproducibility and showed 100% precision in identifying triplicates of upper respiratory tract samples. The single-cartridge Xpert® Xpress system has a short turnaround time and can be employed to improve patient management and hospital bed allocation. Further verification of the system is required before implementation and consideration must be paid to its higher cost and impracticality for high-throughput use.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.008 | 0.011 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".