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

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) conducted in Hong Kong. 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.