Assessment of the clinical and analytical performance of the Aptima SARS-CoV-2 assay using the VALCOR protocol.

BACKGROUND: The COVID-19 pandemic highlighted the importance of diagnostic testing against curbing the spread of SARS-CoV-2. The urgent need and scale for diagnostic tools resulted in manufacturers of SARS-CoV-2 assays receiving emergency authorization that lacked robust analytical or clinical evaluation. As it is highly likely that testing for SARS-CoV-2 will continue to play a central role in public health, the performance characteristics of assays should be evaluated to ensure reliable diagnostic outcomes are achieved. METHODS: VALCOR or "VALidation of SARS-CORona Virus-2 assays" is a study protocol designed to set up a framework for test validation of SARS-CoV-2 virus assays. Using clinical samples collated from VALCOR, the performance of Aptima SARS-CoV-2 assay was assessed against a standard comparator assay. Diagnostic test parameters such as sensitivity, specificity and overall per cent agreement were calculated for the clinical performance of Aptima SARS-CoV-2 assay. RESULTS: A total of 180 clinical samples were tested with an addition of 40 diluted clinical specimens to determine the limit of detection. When compared to the standard comparator assay Aptima had a sensitivity of 100.0% [95% CI 95.9-100.0] and specificity of 96.7% [95% CI 90.8-99.3]. The overall percent agreement was 98.3% with an excellent Cohen's coefficient of κ = 0.967 [95% CI 0.929-1.000]. For the limit of detection, Aptima was able to detect all of the diluted clinical samples. CONCLUSION: In conclusion. validation of Aptima SARS-CoV-2 assay using clinical samples collated through the VALCOR protocol showed excellent test performance. Additionally, Aptima demonstrated high analytical sensitivity by detecting all diluted clinical samples corresponding to a low limit of detection.

VALCOR: a protocol for the validation of SARS-corona virus-2 assays.

BACKGROUND: Testing for SARS-CoV-2, together with vaccination, is one of the most vital strategies in curbing the current COVID-19 pandemic. The pandemic has led to an unprecedented need for diagnostic testing and the rapid emergence of an abundance of commercial assays on the market. Due to the nature of the pandemic and in the interest of health protection, many of these assays received provisional authorisation for emergency use without thorough validation. To limit false negative and false positive results, it is key to define common criteria that SARS-CoV-2 assays need to fulfil. VALCOR or "VALidation of SARS-CORona Virus-2 assays" is a protocol designed to set up a framework for test validation of SARS-CoV-2 virus assays. OBJECTIVES: VALCOR is a study protocol for the validation of assays used for confirmation of the presence of SARS-CoV-2 in patients with COVID-19 disease or the screening of carriers of SARS-CoV-2 virus by the identification of viral RNA in oropharyngeal and/or nasopharyngeal specimens or other specimens from the human respiratory tract. METHODS: The VALCOR panel of samples will contain clinical human specimens and standardised artificial specimens. The collection of clinical specimens will include nasopharyngeal or oropharyngeal specimens or other specimens from the respiratory tract obtained from COVID-19 patients and healthy carriers of SARS-CoV-2 as well as specimens from subjects not carrying SARS-CoV-2. Artificial specimens include calibrated amounts of viral RNA of SARS-CoV-2 sequences provided by established competent agencies that produce reference materials for the assessment of the limit of detection of each assay. The panel of samples are sent from a central reference laboratory (having access to biobanks of clinical specimens tested already for SARS-CoV-2 with a reference comparator assay) to participating laboratories for testing with a SARS-CoV-2 index assay that requires evaluation. DISCUSSION: VALCOR provides a harmonised and standard framework to benchmark the testing performance of SARS-CoV-2 assays that are rapidly evolving. As the pandemic incited an urgent need for testing capacity, there is a gap in the comprehensive validation of SARS-CoV-2 assays. This study will generate comprehensive validation data for assays used for the diagnosis of SARS-CoV-2 and may serve as a basis for other validation protocols.

Evaluation of Pre-Analytical and Analytical Methods for Detecting SARS-CoV-2 in Municipal Wastewater Samples in Northern Italy

(1) Background: The surveillance of SARS-CoV-2 RNA in urban wastewaters allows one to monitor the presence of the virus in a population, including asymptomatic and symptomatic individuals, capturing the real circulation of this pathogen. The aim of this study was to evaluate the performance of different pre-analytical and analytical methods for identifying the presence of SARS-CoV-2 in untreated municipal wastewaters samples by conducting an inter-laboratory proficiency test. (2) Methods: three methods of concentration, namely, (A) Dextran and PEG-6000 two-phase separation, (B) PEG-8000 precipitation without a chloroform purification step and (C) PEG-8000 precipitation with a chloroform purification step were combined with three different protocols of RNA extraction by using commercial kits and were tested by using two primers/probe sets in three different master mixes. (3) Results: PEG-8000 precipitation without chloroform treatment showed the best performance in the SARS-CoV-2 recovery;no major differences were observed among the protocol of RNA extraction and the one-step real-time RT-PCR master mix kits. The highest analytic sensitivity was observed by using primers/probe sets targeting the N1/N3 fragments of SARS-CoV-2. (4) Conclusions: PEG-8000 precipitation in combination with real-time RT-PCR targeting the N gene (two fragments) was the best performing workflow for the detection of SARS-CoV-2 RNA in municipal wastewaters.

Correlations Between Olfactory Psychophysical Scores and SARS-CoV-2 Viral Load in COVID-19 Patients.

OBJECTIVES/HYPOTHESIS: The aim of this study was to evaluate the correlations between the severity and duration of olfactory dysfunctions (OD), assessed with psychophysical tests, and the viral load on the rhino-pharyngeal swab determined with a direct method, in patients affected by coronavirus disease 2019 (COVID-19). STUDY DESIGN: Prospective cohort study. METHODS: Patients underwent psychophysical olfactory assessment with Connecticut Chemosensory Clinical Research Center test and determination of the normalized viral load on nasopharyngeal swab within 10 days of the clinical onset of COVID-19. RESULTS: Sixty COVID-19 patients were included in this study. On psychophysical testing, 12 patients (20% of the cohort) presented with anosmia, 11 (18.3%) severe hyposmia, 13 (18.3%) moderate hyposmia, and 10 (16.7%) mild hyposmia with an overall prevalence of OD of 76.7%. The overall median olfactory score was 50 (interquartile range [IQR] 30-72.5) with no significant differences between clinical severity subgroups. The median normalized viral load detected in the series was 2.56E+06 viral copies/106 copies of human beta-2microglobulin mRNA present in the sample (IQR 3.17E+04-1.58E+07) without any significant correlations with COVID-19 severity. The correlation between viral load and olfactory scores at baseline (R2  = 0.0007; P = .844) and 60-day follow-up (R2  = 0.0077; P = .519) was weak and not significant. CONCLUSIONS: The presence of OD does not seem to be useful in identifying subjects at risk for being super-spreaders or who is at risk of developing long-term OD. Similarly, the pathogenesis of OD is probably related to individual factors rather than to viral load and activity. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:2312-2318, 2021.