Comparison of nasopharyngeal swab and nasopharyngeal aspiration in adults for SARS-CoV-2 identification using reverse transcription-polymerase chain reaction

Abstract

We aimed to compare reverse transcription-polymerase chain reaction (RT-PCR) results of nasopharyngeal aspiration (NA) and nasopharyngeal swab (NS) samples in the diagnosis of coronavirus disease 2019. NS was obtained with a dacron swab and NA was performed by aspiration cannula. The sampling was performed by an otolaryngologist to ensure standardized correct sampling from the nasopharynx. RT-PCR was performed for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The level of agreement between the result of NA and NS samples for each patient was analyzed. The Ct values were compared. Thirty-three patients were enrolled in the study with a mean age of 56.3 years. Thirteen subjects resulted negative with both NS and NA; 20 subjects resulted positive with NA and 18 subjects resulted positive with NS. The mean values of Ct for NA samples and NS samples were 24.6 ± 5.9 and 24 ± 6.7, respectively. There was no statistical difference between Ct values of NA and NS samples (p = 0.48). RT-PCR for SARS-Cov2 performed with NA sample and NS sample showed a strong correlation regarding the positivity/negativity and the Ct values.