Background: As the global pandemic of severe acute respiratory syndrome coronavirus-2 continues, so does the need for molecular tests with simple, painless, and easy sample collection. We aimed to investigate the potential use of saliva and anterior nasal swab samples as a noninvasive and self-collectable specimen for the molecular diagnosis of coronavirus disease 2019 (COVID-19).
Methods: We prospectively collected the saliva, anterior nasal swab, and conventional nasopharyngeal swab samples at the same time of patients hospitalized in a public hospital from March 2021 to September 2021. Patients were assessed for symptoms, and real-time polymerase chain reaction (RT-PCR) was performed on the samples. The results and cyclethresholds (Ct) of the three sample types were compared.
Results: Three types of samples per patient were collected, and a total of 135 samples were collected. The mean age of the patients was 39.5 years (range, 9–71 years). The positive rates were 82.2% for nasopharyngeal swab samples, 35.6% for anterior nasal swab samples, and 55.6% for saliva samples. No significant differences in the Ct values between samples (P=0.256) were observed when comparing only the sets which were positive in all three sample types. Using nasopharyngeal swab RT-PCR as the reference standard, the sensitivity and specificity of the combined saliva and anterior nasal swab RT-PCR were 70.3% and 62.5%, respectively.
Conclusions: Saliva and anterior nasal swab samples could not be used as alternative samples for COVID-19 diagnosis. Further studies with a larger number of patients are needed in the future.

Keywords: SARS-CoV-2, COVID-19, Real-time polymerase chain reaction, Nasopharyngeal swab, Saliva, Anterior nasal swab