The Ability to Detect the COVID-19 Genome Using Saliva Swabs in Comparison with Nasopharyngeal Swabs in Baghdad

Abstract

Objective Nasopharyngeal swab (NPS) sampling has been recommended by the World Health Organization (WHO) since the start of the COVID-19 pandemic, and real-time reverse transcription polymerase chain reaction (RT–PCR) is used to detect SARS-CoV- 2, the causative agent of COVID-19. This sampling technique is invasive and causes discomfort to the patient. Saliva swabs (SSs) can be used as an alternative noninvasive method; however, there are limited data confirming its suitability for the diagnosis of COVID-19. The aim of this study was to test the ability to detect COVID-19 using SSs in comparison with NPSs in the Baghdad Alkark sector. Materials and Methods Six hundred and fifty patients were included in this study, and written informed consent was obtained from all the study participants. Paired NPSs and SSs were collected at the same time from each participant between days 3 and 5 after disease initiation. SSs were taken from the sublingual area. An RT‒PCR assay was used to detect the viral ribonucleic acid (RNA) of SARS-CoV-2 for the diagnosis of COVID-19. The chi-squared test was used for data analysis, with p < 0.05 considered significant. Results Out of 650 participants with suspected COVID-19 (313 males and 145 females), 313 were confirmed to be positive for COVID-19 by quantitative RT–PCR (RT‒qPCR) using both samples. The ages ranged between 12 and 85 years, with a mean/standard deviation (SD) of 45.45 (16.62) years. All the cases with positive results using NPSs were also positive when SSs were used. Statistically, there was no significant difference between the two groups (p = 0.347). Conclusion RT‒PCR assays conducted on SSs and NPSs performed similarly, indicating that SSs may be a safe, inexpensive diagnostic sampling method and an effective tool for population screening. We recommend more studies to support this finding.