Assessment of SARS-CoV-2 viral loads in combined nasal-and-throat swabs collected from COVID-19 individuals under the Universal Community Testing Programme in Hong Kong

Abstract Background Combined nasal-and-throat swabs (CNTS) is less invasive and easy to execute. CNTS also induces lower risk to healthcare workers upon collection. However, there is a lack of data on viral load assessment for population-wide testing. Objective This study assessed if CNTS is suitable as an alternative specimen type for the detection of SARS-CoV-2. Methods We assessed the viral load of SARS-CoV-2 in CNTS collected from COVID-19 individuals through the 2-week period of the Universal Community Testing Programme (UCTP). In addition, we compared viral loads of SARS-CoV-2 for the paired CNTS and non-CNTS specimens among these individuals. Results This UCTP identified 48 COVID-19 individuals from nearly 2 million specimens collected. The viral loads of SARS-CoV-2 varied widely, cycle threshold values Ct 16.28 - 36.94, among symptoms and asymptomatic individuals. The viral loads for the paired CNTS and non-CNTS specimens were comparable. Conclusions This study demonstrated that CNTS could be a specimen of choice for diagnosis of SARS-CoV-2.