Optimizing oropharyngeal swabbing techniques: the relationship between force applied and SARS-CoV-2 detection sensitivity.

Aim: Nasopharyngeal and oropharyngeal swabs are essential for diagnosing SARS-CoV-2 infections, with nucleic acid testing (NAT) being the most sensitive method. However, NAT results are heavily influenced by preanalytical factors, including quality of the sample. This study examines the effect of applied force during oropharyngeal sampling on sample quality, specifically assessing cell count and the associated NAT cycle threshold (Ct) values. Methods: A three-phase investigation was conducted to explore the relationship between sampling force and cell quantity, as well as the impact of cell count on NAT sensitivity. Results: A significantly lower Ct value was achieved by artificially increasing the cell count in a swab sample and applying a greater force resulted in higher cell counts, but the opposite effect on Ct values of SARS-CoV-2 NAT was shown. Conclusion: These findings indicate that while applying greater force during sample collection increases the number of collected cells, it does not improve the sensitivity of SARS-CoV-2 detection and can even lead to poorer results. Further research should focus on optimizing swab design to improve sample quality and the number of cells obtained.