Table 1. Coronavirus disease (COVID-19) outbreak preparedness EQA pilot study, panel composition and overall performance per sample, April/May 2020 (n =521).
| Sample code | Sample contenta | Viral RNA concentrationb
(dPCR log10 copies/mL) |
Sample statusc | Percentage correct qualitative results (all) | Reported Cq values (For information purposes only) |
||
|---|---|---|---|---|---|---|---|
| % | Total datasets | Median (range) | Total datasets | ||||
| CVOP20S-01 | SARS-CoV-2 | 4.30 | CORE | 98.1 | 521 | 29.1 (15.8–41.6) |
449 |
| CVOP20S-02 | HCoV-NL63 | 4.64 | EDUC | 96.9 | 521 | NA | NA |
| CVOP20S-03 | SARS-CoV-2 | 3.30 | CORE | 96.9 | 521 | 32.2 (18.0–43.0) |
450 |
| CVOP20S-04 | HCoV-OC43 | 4.03 | EDUC | 97.1 | 521 | NA | NA |
| CVOP20S-05 | Negative | NA | CORE | 97.3 | 521 | NA | NA |
| CVOP20S-06 | SARS-CoV-2 | 4.30 | CORE | 98.5 | 521 | 29.2 (16.6–40.0) |
450 |
| CVOP20S-07 | SARS-CoV-2 | 5.30 | CORE | 99.2 | 521 | 25.9 (12.0–39.0) |
453 |
| CVOP20S-08 | SARS-CoV-2 | 2.30 | CORE | 86.0 | 521 | 35.0 (22.7–43.3) |
400 |
Cq: quantification cycle; CVOP: Coronavirus outbreak preparedness; dPCR: digital PCR; EQA: external quality assessment; HCoV: human coronavirus: NA: not applicable; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2.
a Content of the EQA samples: SARS-CoV-2 strain BetaCoV/Munich/ChVir984/2020 provided by the Charité-Universitätsmedizin Berlin Institute of Virology, Berlin, Germany; human coronaviruses HCoV-NL63 and HCoV-OC43 cultivated by the University Medical Center Groningen, Groningen, the Netherlands, and sample specifications selected based on past performance data from regular provided coronavirus EQA schemes; negative control sample contained transport medium only (which was used as sample matrix for the EQA samples).
b Values obtained using a dPCR assay (modified from [6]). Samples CVOP20S-07, -01, -03 and - 08 are in a calibrated dilution series. CVOP20S-06 is a duplicate sample of CVOP20S-01. The values provided are for reference only and have been established to support the consistency and traceability of the EQA materials as well as comparison of results across participating laboratories.
c EQA samples are defined as ‘CORE’ or ‘EDUC’ (educational). Core proficiency samples are reviewed by scientific experts, based on scientific information, clinical relevance, current literature and where appropriate, professional clinical guidelines. Participating laboratories were expected to report the core proficiency samples (here: all SARS-CoV-2-positive samples and the negative control) correctly within the EQA scheme. Samples CVOP20S-02 and CVOP20S-04 were included in the panel as educational specificity samples and were expected to be reported as SARS-CoV-2 negative. Participants were not expected to report on the identity of the common human coronaviruses HCoV-NL63 or HCoV-OC43.