ABSTRACT
IMPORTANCESince December, 2020, the ID NOW was implemented for use in 4 different populations across Alberta: in mobile units as part of community outbreak response, COVID-19 community collection sites, emergency shelters and addiction treatment facilities (ES), and hospitals. OBJECTIVEDiagnostic evaluation of the ID NOW in various real world settings among symptomatic and asymptomatic individuals DESIGNDepending on the implemented site, the ID NOW was tested on patients with symptoms suggestive of COVID-19, asymptomatic close contacts or asymptomatic individuals as part of outbreak point prevalence screening. From Jan - April, a select number of sites also switched from using oropharyngeal swabs to combined oropharyngeal + nasal (O+N) swabs. For every individual tested, two swabs were collected: one for ID NOW testing and the other for either reverse-transcriptase polymerase chain reaction (RT-PCR) confirmation of negative ID NOW results or for variant testing of positive ID NOW results. RESULTSA total of 129,112 paired samples were analyzed (16,061 RT-PCR positive). 81,697 samples were from 42 COVID-19 community collection sites, 16,924 from 69 rural hospitals, 1,927 from 9 ES, 23,802 samples from 6 mobile units that responded to 356 community outbreaks, and 4,762 from 3 community collection sites and 1 ES using O+N swabs for ID NOW testing. ID NOW sensitivity was highest among symptomatic individuals presenting to community collection sites [92.5%, 95% confidence interval (CI) 92.0-93.0%, n=10,633 RT-PCR positive] and lowest for asymptomatic individuals associated with community outbreaks (73.9%, 95% CI 69.8-77.7%, n=494 RT-PCR positive). Specificity was greater than 99% in all populations tested, but positive predictive value (PPV) was lower among asymptomatic populations (82.4-91.3%) compared to symptomatic populations (96.0-96.9%). There was no statistically significant differences in sensitivity with respect to age, gender, NP vs OP swab for RT-PCR confirmation, variants of concern, or with combined oropharyngeal and nasal swabs using COVID-19 ID NOW testing. CONCLUSIONSSensitivity of ID NOW SARS-CoV-2 testing is highest when used on symptomatic community populations not seeking medical care. Sensitivity and PPV drops by approximately 10% when tested on asymptomatic populations. Using combined oropharyngeal and nasal swabs did not improve ID NOW performance.
ABSTRACT
BACKGROUNDPoint of Care Testing (POCT) SARS-CoV-2 antigen tests, such as the Abbott Panbio, have great potential to help combat the COVID-19 pandemic. The Panbio is Health Canada approved for the detection of SARS-CoV-2 in symptomatic individuals within the first 7 days of COVID-19 symptom onset(s). METHODSSymptomatic adults recently diagnosed with COVID-19 in the community were recruited into the study. Paired nasopharyngeal (NP), throat, and saliva swabs were collected, with one paired swab tested immediately with the Panbio, and the other transported in universal transport media and tested using reverse-transcriptase polymerase chain reaction (RT-PCR). Positive percent agreement (PPA) was calculated. Subsequently, individuals within 7 days of symptom onset who presented to community assessment centres for SARS-CoV-2 testing had Panbio testing completed and paired with RT-PCR results from parallel NP or throat swabs. RESULTS145 individuals were included in the study. Collection of throat and saliva was stopped early due to poor performance (throat PPA 57.7%, n=61, and saliva PPA 2.6%, n=41). NP swab PPA was 87.7% [n=145, 95% confidence interval 81.0% - 92.7%]. There were 1,641 symptomatic individuals tested by Panbio in community assessment centres, with 268/1641 (16.3%) positive for SARS-CoV-2. There were 37 false negatives, corresponding to a PPA of 86.2% [81.5% - 90.1%]. CONCLUSIONSThe Panbio test reliably detects most cases of SARS-CoV-2 from adults in the POCT community setting presenting within 7 days of symptom onset using nasopharyngeal swabs. Throat and saliva swabs are not reliable specimens for the Panbio.
ABSTRACT
INTRODUCTIONPoint of care diagnostic tests for SARS-CoV-2, such as the ID NOW, have great potential to help combat the COVID-19 pandemic. The ID NOW is approved by the United States Food and Drug Administration (FDA) for the detection of SARS-CoV-2 in symptomatic individuals within the first 7 days of symptom onset for COVID-19 if tested within 1 hour of specimen collection. However, clinical data on the performance of the ID NOW is limited, with many studies deviating from the manufacturers instructions and/or having small sample size. METHODSAdults with COVID-19 in the community or hospital were recruited into the study. Paired throat swabs were collected, with one throat swab transported immediately in an empty sterile tube to the laboratory for ID NOW testing, and the other transported in universal transport media and tested by an in-house SARS-CoV-2 RT-PCR assay targeting the E-gene. Positive percent agreement (PPA) was calculated. RESULTS133 individuals were included in the study. 129 samples were positive on either the ID NOW and/or RT-PCR. Assuming any positive result on either assay represents a true positive, PPA of the ID NOW compared to RT-PCR with 95% confidence intervals was 89.1% [82.0% - 94.1%] and 91.6% [85.1% - 95.9%], respectively. When analyzing individuals with symptoms [≤] 7 days and who had the ID NOW performed within an hour, ID NOW PPA increased to 98.2%. DISCUSSIONIn this study, SARS-CoV-2 results from the ID NOW were reliable, especially when testing was adhered to manufacturers recommendations.
ABSTRACT
Saliva samples were collected through a simple mouth wash procedure and viral load quantified using a technology called digital droplet PCR. Data suggest ddPCR allows for precise quantification of viral load in clinical samples infected with SARS-CoV-2.
ABSTRACT
We have developed a reverse-transcriptase loop mediated amplification (RT-LAMP) method targeting genes encoding the Spike (S) protein and RNA-dependent RNA polymerase (RdRP) of SARS-CoV-2. The LAMP assay achieves comparable limit of detection as commonly used RT-PCR protocols based on artificial targets, recombinant Sindbis virus, and clinical samples. Clinical validation of single-target (S gene) LAMP (N=120) showed a positive percent agreement (PPA) of 41/42 (97.62%) and negative percent agreement (NPA) of 77/78 (98.72%) compared to reference RT-PCR. Dual-target RT-LAMP (S and RdRP gene) achieved a PPA of 44/48 (91.97%) and NPA 72/72 (100%) when including discrepant samples. The assay can be performed without a formal extraction procedure, with lyophilized reagents which do need cold chain, and is amenable to point-of-care application with visual detection.
