Mass screening of asymptomatic persons for SARS-CoV-2 using saliva

BackgroundCOVID-19 has rapidly evolved to become a global pandemic due largely to the transmission of its causative virus through asymptomatic carriers. Detection of SARS-CoV-2 in asymptomatic people is an urgent priority for the prevention and containment of disease outbreaks in communities. However, few data are available in asymptomatic persons regarding the accuracy of PCR testing. Additionally, although self-collected saliva has significant logistical advantages in mass screening, its utility as an alternative specimen in asymptomatic persons is yet to be determined. MethodsWe conducted a mass-screening study to compare the utility of nucleic acid amplification, such as reverse transcriptase polymerase chain reaction (RT-PCR) testing, using NPS and saliva samples from each individual in two cohorts of asymptomatic persons: the contact tracing cohort and the airport quarantine cohort. ResultsIn this mass-screening study including 1,924 individuals, the sensitivity of nucleic acid amplification testing with nasopharyngeal and saliva specimens were 86% (90%CI:77-93%) and 92% (90%CI:83-97%), respectively, with specificities greater than 99.9%. The true concordance probability between the nasopharyngeal and saliva tests was estimated at 0.998 (90%CI:0.996-0.999) on the estimated airport prevalence, 0.3%. In positive individuals, viral load was highly correlated between NPS and saliva. ConclusionBoth nasopharyngeal and saliva specimens had high sensitivity and specificity. Self-collected saliva is a valuable specimen to detect SARS-CoV-2 in mass screening of asymptomatic persons.

Feasibility of Endoscopic Papillary Large Balloon Dilation in Patients with Difficult Bile Duct Stones without Dilatation of the Lower Part of the Extrahepatic Bile Duct

BACKGROUND/AIMS: There is no consensus for using endoscopic papillary large balloon dilation (EPLBD) in patients without dilatation of the lower part of the bile duct (DLBD). We evaluated the feasibility and safety of EPLBD for the removal of difficult bile duct stones (diameter ≥10 mm) in patients without DLBD. METHODS: We retrospectively reviewed the records of 209 patients who underwent EPLBD for the removal of bile duct stones from October 2009 to July 2014. Primary outcomes were the clearance rate and additional mechanical lithotripsy. Secondary outcomes were the incidence of complications and recurrence rate. RESULTS: Fifty-seven patients had DLBD (27.3%), and 152 did not have DLBD (72.7%). There were no significant differences in the overall success rate or the use of mechanical lithotripsy. Success rate during the first session and procedure time were better in the DLBD than the without-DLBD group (75.7% vs 66.7%, 48.1±23.0 minutes vs 58.4±31.7 minutes, respectively). As for complications, there were no significant differences in the incidence of pancreatitis, perforation or bleeding after endoscopic retrograde cholangiopancreatography. The recurrence rate did not differ significantly between the two groups. CONCLUSIONS: EPLBD is a useful and safe method for common bile duct stone removal in patients without DLBD.