ABSTRACT
Using a real-time RT-PCR-based algorithm to detect SARS-CoV-2 variants of concern, we rapidly identified 77 variants (57-B.1.1.7, 7-B.1.351, and 13-B.1.1.28/P.1). This protocol enabled our laboratory to screen all SARS-CoV-2 positive samples for variants, and identified a cluster of B.1.1.28/P.1 cases, a variant not previously known to circulate in British Columbia.
ABSTRACT
Due to global shortages of flocked nasopharyngeal swabs and appropriate viral transport media during the COVID-19 pandemic, alternate diagnostic specimens for SARS-CoV-2 detection are sought. The accuracy and feasibility of saliva samples collected and transported without specialized collection devices or media were evaluated. Saliva demonstrated good concordance with paired nasopharyngeal swabs for SARS-CoV-2 detection in 67/74 cases (90.5%), though barriers to saliva collection were observed in long-term care residents and outbreak settings. SARS-CoV-2 RNA was stable in human saliva at room temperature for up to 48 hours after initial specimen collection, informing appropriate transport time and conditions.
ABSTRACT
Nasopharyngeal swabs are critical to the diagnosis of respiratory infections including COVID-19, but collection techniques vary. We compared two recommended nasopharyngeal swab collection techniques in adult volunteers and found that swab rotation following nasopharyngeal contact did not recover additional nucleic acid (as measured by human DNA/RNA copy number). Rotation was also less tolerable for participants. Notably, both discomfort and nucleic acid recovery were significantly higher in Asians, consistent with nasal anatomy differences. Our results suggest that it is unnecessary to rotate the swab in place following contact with the nasopharynx, and reveal that procedural discomfort levels can differ by ethnicity. summaryNasopharyngeal swabs are critical to COVID-19 diagnostics, but collection techniques vary. Comparison of two collection techniques revealed that swab rotation did not recover more nucleic acid and was more uncomfortable. Discomfort and biological material recovery also varied by participant ethnicity.
ABSTRACT
With surging global demand for increased SARS-CoV-2 testing capacity, clinical laboratories seek automated, high-throughput molecular solutions, particularly for specimen types which do not rely upon supply of specialized collection devices or viral transport media (VTM). Saliva was evaluated as a diagnostic specimen for SARS-CoV-2 using the cobas(R) SARS-CoV-2 Test on the cobas(R) 6800 instrument. Saliva specimens submitted from various patient populations under investigation for COVID-19 from March-July 2020 were processed in the laboratory with sterile phosphate-buffered saline in a 1:2 dilution and vortexed with glass beads. The processed saliva samples were tested using a commercial assay for detection of the SARS-CoV-2 E gene (LightMix(R)) in comparison to the cobas(R) SARS-CoV-2 Test. 22/64 (34.4%) of the saliva samples were positive for SARS-CoV-2. Positive and negative concordance between the LightMix(R) and cobas(R) assays were 100%. There was no cross-contamination of samples observed on the cobas(R) 6800. The overall invalid rate for saliva on the cobas(R) 6800 (1/128, 0.78%) was similar to the baseline invalid rate observed for nasopharyngeal swabs/VTM and plasma samples. Saliva is a feasible specimen type for SARS-CoV-2 testing on the cobas(R) 6800, with potential to improve turnaround time and enhance testing capacity.
ABSTRACT
Improper nasopharyngeal swab collection could contribute to false-negative COVID-19 results. In support of this, specimens from confirmed or suspected COVID-19 cases that tested negative or indeterminate (i.e. suspected false-negatives) contained less human DNA (a stable molecular marker of sampling quality) compared to a representative pool of specimens submitted for testing.
