Nationwide Harmonization Effort for Semi-Quantitative Reporting of SARS-CoV-2 PCR Test Results in Belgium.

From early 2020, a high demand for SARS-CoV-2 tests was driven by several testing indications, including asymptomatic cases, resulting in the massive roll-out of PCR assays to combat the pandemic. Considering the dynamic of viral shedding during the course of infection, the demand to report cycle threshold (Ct) values rapidly emerged. As Ct values can be affected by a number of factors, we considered that harmonization of semi-quantitative PCR results across laboratories would avoid potential divergent interpretations, particularly in the absence of clinical or serological information. A proposal to harmonize reporting of test results was drafted by the National Reference Centre (NRC) UZ/KU Leuven, distinguishing four categories of positivity based on RNA copies/mL. Pre-quantified control material was shipped to 124 laboratories with instructions to setup a standard curve to define thresholds per assay. For each assay, the mean Ct value and corresponding standard deviation was calculated per target gene, for the three concentrations (107, 105 and 103 copies/mL) that determine the classification. The results of 17 assays are summarized. This harmonization effort allowed to ensure that all Belgian laboratories would report positive PCR results in the same semi-quantitative manner to clinicians and to the national database which feeds contact tracing interventions.

A brief performance evaluation and literature review of Abbott ID Now COVID-19 rapid molecular-based test.

The qualitative ID Now COVID-19 assay combines claimed performance and ease of use that seem to position it as a reliable test for urgent patient management. However, the declared limit of detection (LOD) of 125 genome equivalents/mL is not confirmed by the published studies, which observed a range of LOD varying from 276 to 20.000 copies/mL. We decided to establish the LOD value on more robust basis using serial dilutions of a SARS-CoV-2 culture supernatant sample of defined concentration. Afterwards, we tested the analytical performances of the assay with 23 QCMD external quality control measurements. Hence, taking into consideration the additional dilution in the sample receiver cup, we found a lower 95 % LOD of 64 copies/mL. For its intended use and with the new established LOD, ID Now COVID-19 proved to be a suitable test for the diagnosis of COVID-19 in contagious patients, as proposed by the latest Belgian recommendations.

Reuse of Clinical COVID-19 Patient Data: Pre-Processing for Future Classification.

One of the most important challenges in the scenario of COVID-19 is to design and develop decision support systems that can help medical staff to identify a cohort of patients that is more likely to have worse clinical evolution. To achieve this objective it is necessary to work on collected data, pre-process them in order to obtain a consistent dataset and then extract the most relevant features with advanced statistical methods like principal component analysis. As preliminary results of this research, very influential features that emerged are the presence of cardiac and liver illnesses and the levels of some inflammatory parameters at the moment of diagnosis.