RESUMO
BACKGROUND: Nasopharyngeal antigen Rapid Diagnostic Tests (RDTs), saliva RT-PCR and nasopharyngeal (NP) RT-PCR have shown different performance characteristics to detect patients infected by SARS-CoV-2, according to the viral load (VL)-and thus transmissibility. METHODS: In October 2020, we conducted a prospective trial involving patients presenting at testing centres with symptoms of COVID-19. We compared detection rates and performance of RDT, saliva PCR and nasopharyngeal (NP) PCR, according to VL and symptoms duration. RESULTS: Out of 949 patients enrolled, 928 patients had all three tests performed. Detection rates were 35.2% (95%CI 32.2-38.4%) by RDT, 39.8% (36.6-43.0%) by saliva PCR, 40.1% (36.9-43.3%) by NP PCR, and 41.5% (38.3-44.7%) by any test. For those with viral loads (VL) ≥106 copies/ml, detection rates were 30.3% (27.3-33.3), 31.4% (28.4-34.5), 31.5% (28.5-34.6), and 31.6% (28.6-34.7%) respectively. Sensitivity of RDT compared to NP PCR was 87.4% (83.6-90.6%) for all positive patients, 94.5% (91.5-96.7%) for those with VL≥105 and 96.5% (93.6-98.3%) for those with VL≥106. Sensitivity of STANDARD-Q®, Panbio™ and COVID-VIRO® Ag tests were 92.9% (86.4-96.9%), 86.1% (78.6-91.7%) and 84.1% (76.9-89.7%), respectively. For those with VL≥106, sensitivity was 96.6% (90.5-99.3%), 97.8% (92.1-99.7%) and 95.3% (89.4-98.5%) respectively. No patient with VL<104 was detected by RDT. Specificity of RDT was 100% (99.3-100%) compared to any PCR. RDT sensitivity was similar <4 days (87.8%, 83.5-91.3%) and ≥4 days (85.7%, 75.9-92.6%) after symptoms onset (p = 0.6). Sensitivity of saliva and NP PCR were 95.7% (93.1-97.5%) and 96.5% (94.1-98.1%), respectively, compared to the other PCR. CONCLUSIONS: RDT results allow rapid identification of COVID cases with immediate isolation of most contagious individuals. RDT can thus be a game changer both in ambulatory care and community testing aimed at stopping transmission chains, and even more so in resource-constrained settings thanks to its very low price. When PCR is performed, saliva could replace NP swabbing. TRIAL REGISTRATION: ClinicalTrial.gov Identifier: NCT04613310 (03/11/2020).
Assuntos
COVID-19 , SARS-CoV-2 , Humanos , Antígenos Virais , Teste para COVID-19 , Reação em Cadeia da Polimerase , Estudos Prospectivos , Saliva , Sensibilidade e EspecificidadeRESUMO
Many of our medical procedures are conditioned by beliefs or experiences by our mentors, which we pass on to the younger, for example: gradually emptying a full bladder to avoid hypotension or haemorrhage, hydrating the alcoholic so that the blood alcohol level decreases faster, always obtaining an arterial blood gas instead of a venous one and not injecting iodinated intravenous contrast in patients allergic to shellfish.
Un bon nombre de nos actes médicaux sont conditionnés par les croyances ou les expériences enseignées par nos mentors que nous transmettons à notre tour aux plus jeunes : vider progressivement un globe urinaire pour éviter une hypotension artérielle ou une hémorragie, hydrater les alcoolisés pour que leur alcoo-lémie baisse plus vite, toujours réaliser une gazométrie artérielle au lieu de veineuse et ne pas injecter de produits de contraste iodés chez les allergiques aux crustacés sont des exemples.
Assuntos
Serviços Médicos de Emergência , Hemorragia , Hemorragia/terapia , HumanosRESUMO
A high quality Ca(5)(BO(3))(3)F (CBF) crystal, grown by flux method, was investigated for its non linear optical properties. This material is non hygroscopic and possesses a moderate birefringence suitable for UV light generation. On the basis of its refractive index dispersion curves, it is inferred that CBF has great potential applications as non linear optical material, notably for UV light generation at 355 and 266 nm. In order to characterize its non linear optical properties, CBF samples were first cut and oriented in phase matching conditions for second harmonic generation of 1064 nm. Experimental results demonstrate that CBF has the moderate NLO coefficients. The optical conversion efficiency from 1064 nm to 532 nm was investigated for the first time: up to 54% were achieved. Non linear d(eff) coefficients were also estimated as well as the external angular acceptance bandwidth of SHG at 1064 nm.
