Prospective study of three saliva qualitative antigen testing kits for the detection of SARS-CoV-2 among mainly symptomatic patients in Japan

• Published in: Journal of infection and chemotherapy : official journal of the Japan Society of Chemotherapy 2023-07, Vol.29 (7), p.654-659
• Main Authors: Terada, Norihiko, Akashi, Yusaku, Takeuchi, Yuto, Ueda, Atsuo, Notake, Shigeyuki, Nakamura, Koji, Suzuki, Hiromichi
• Format: Article
• Language: English
• Subjects: COVID-19; COVID-19 - diagnosis; Humans; Japan; Nasopharynx; Original; Prospective Studies; Qualitative antigen testing; Saliva; Saliva sample; SARS-CoV-2; Sensitivity and Specificity; Specimen Handling
• ISSN: 1341-321X; 1437-7780; 1437-7780
• DOI: 10.1016/j.jiac.2023.03.005

Rapid qualitative antigen testing has been widely used for the laboratory diagnosis of COVID-19 with nasopharyngeal samples. Saliva samples have been used as alternative samples, but the analytical performance of those samples for qualitative antigen testing has not been sufficiently evaluated. A prospective observational study evaluated the analytical performance of three In Vitro Diagnostics (IVD) approved COVID-19 rapid antigen detection kits for saliva between June 2022 and July 2022 in Japan using real-time reverse transcription polymerase chain reaction (RT-qPCR) as a reference. A nasopharyngeal sample and a saliva sample were simultaneously obtained, and RT-qPCR was performed. In total, saliva samples and nasopharyngeal samples were collected from 471 individuals (RT-qPCR-positive, n = 145) for the analysis. Of these, 96.6% were symptomatic. The median copy numbers were 1.7 × 106 copies/mL for saliva samples and 1.2 × 108 copies/mL for nasopharyngeal samples (p 107 copies/mL), whereas the sensitivities were 107 copies/mL). COVID-19 rapid antigen detection kits with saliva showed high specificity, but the sensitivity varied among kits, and were also insufficient for the detection of symptomatic COVID-19 patients.