BACKGROUND The high demand for adequate material for the gold standard reverse transcription real-time polymerase chain reaction (RT-qPCR)-based diagnosis imposed by the Coronavirus disease 2019 (COVID-19) pandemic, combined with the inherent contamination risks for healthcare workers during nasopharyngeal swab (NP) sample collection and the discomfort it causes patients, brought the need to identify alternative specimens suitable for the diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). OBJECTIVES The aim of this work was to compare saliva and gingival fluid swabs to NP swabs as specimens for RT-qPCR-based SARS-CoV-2 diagnosis. METHODS We compared gingival fluid swabs (n = 158) and saliva (n = 207) to the rayon-tipped NP swabs obtained from mild-symptomatic and asymptomatic subjects as specimens for RT-qPCR for SARS-CoV-2 detection. FINDINGS When compared to NP swabs, gingival fluid swabs had a concordance rate of 15.4% among positive samples, zero among inconclusive, and 100% among negative ones. For saliva samples, the concordance rate was 67.6% among positive samples, 42.9% among inconclusive, and 96.8% among negative ones. However, the concordance rate between saliva and NP swabs was higher (96.9%) within samples with lower cycle threshold (Ct) values (Ct > 10 ≤ 25). MAIN CONCLUSIONS Our data suggests that whereas gingival fluid swabs are not substitutes for NP swabs, saliva might be considered whenever NP swabs are not available or recommended.
This paper consists of the first lecture notes published originally in the November 1931 issue of the Bulletin of the Engineering Institute, p. 157-166. Here the basic concepts of the physics of waves and geometrical optics are discussed and the analogy between the classical mechanics and geometrical optics is explored towards the introduction of the Schrödinger undulatory mechanics.
Este artigo consiste nas notas da primeira conferência publicado originalmente no número de Novembro de 1931 no Boletim do Instituto de Engenharia, pp. 157-166. Aqui os conceitos básicos da física ondulatoria e da óptica geométrica são discutidos e a analogia entre a mecânica clássica e a óptica geométrica é explorada com vistas a introdução da mecânica ondulatória de Schrödinger.