Comparative Analysis of SARS-Cov-2 Detection Using Viral Swab in Viral Transport Medium Against Cotton Swab in 0.9% Normal Saline

Résumé fourni par la source

Coronavirus Disease 2019 (COVID-19) has become a major health problem causing severe acute respiratory illness in humans. With the high case count and mortality rate, a broad testing method is required to detect the virus in infected people, as well as less common clinical manifestations of the disease. Consequently, the high demand for testing has resulted in a depletion of commercially available consumables, including the recommended swabs and viral transport media (VTM) required for oropharyngeal sampling. To address this issue, we evaluated the utility of a commonly found cotton swab in 0.9% normal saline against the viral swab in viral transport medium (VTM) for the molecular detection of SARS-CoV-2. The study was a cross-sectional analytical study that recruited 322 suspected COVID-19 patients from Kwadaso Seventh Day Adventist and Suntreso Government Hospitals, Kumasi, Ghana, between April and September 2021. Consecutive oropharyngeal swab samples were obtained with viral swabs and cotton swabs in parallel and inserted into the viral transport medium and 0.9% normal saline, respectively. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was performed on the samples concurrently for detection of SARS-CoV-2 genes (N and ORF1ab genes). Comparison of the cotton swab in 0.9% saline samples to the viral swab in VTM samples, yielded the following results: the cotton swab samples were 61.9% (51.7-71.2) sensitive, 96.9% (93.8- 98.5) specific, and with positive and negative predictive values of 89.0% and 86.4% respectively. The median viral load was significantly higher in samples taken with a viral swab in VTM (276, IQR: 51.49- 9837.87) compared to samples taken with a cotton swab in 0.9% saline (252.86, IQR: 29.62-4235.93), p = 0.0059. Our study suggests that cotton swabs in 0.9% saline have low sensitivity and viral yield and hence not appropriate for collection of respiratory samples for SARSCoV-2 detection.

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