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Tag: testing
February 26, 2021
The Effects of “Dry Swab” Incubation on SARS-CoV-2 Molecular Testing
Parikh et al. suggest that “dry swabs” (which do not use transport medium) may be accurate for SARS-CoV-2 diagnostics. Flocked swabs were inoculated with SARS-CoV-2 and then incubated in either the typical medium or a dry, sterile conical tube. All dry swabs tested at days 1, 2, and 7 provided results that were within two…
February 24, 2021
Self-Testing for the Detection of SARS-CoV-2 Infection with Rapid Antigen Tests
[Pre-print, not peer-reviewed] Self-testing for SARS-CoV-2 using rapid antigen detection kits (RDT) was found to have a high specificity (99.4%) and relatively high sensitivity (78%) to identify individuals infected with SARS-CoV-2 RNA below a low cycle-time (CT) value threshold. Low CT values are associated with high viral load and the authors suggest that is a…
February 23, 2021
Correlation of SARS-CoV-2 RNA in Wastewater with COVID-19 Disease Burden in Sewersheds
COVID-19 outbreaks across two Utah communities positively correlated with an increase in wastewater SARS-CoV-2 RNA. Wastewater surveillance only cost $0.005-$0.10 per capita, according to a wastewater epidemiology study conducted in 10 wastewater facilities covering approximately 1.26 million Utah residents. Overall, RNA was detected in 61% of 126 wastewater samples. Weidhaas et al. (Feb 12, 2021). Correlation…
Saliva for Molecular Detection of SARS-CoV-2 in School-Aged Children
Saliva RT-PCR had a sensitivity of 88% and specificity of 99% compared to nasopharyngeal swabs (NPS) in a study of 485 NPS and saliva sample pairs collected from 476 children presenting for COVID-19 screening in Dubai. Viral detection in at least one specimen type was reported in 18%, with 17% in NPS alone and 16%…
February 19, 2021
SARS-CoV-2 Positivity on or After 9 Days Among Quarantined Student Contacts of Confirmed Cases
Among student contacts of confirmed COVID-19 cases in Florida between August and November 2020, a protocol requiring a negative RT-PCR test as early as day 9 of quarantine reduced the loss of instruction days compared to a conventional 14-day quarantine without testing. The number of missed days decreased by 3,649 days with the 9-day testing…
Multicenter Evaluation of the PanbioTM COVID-19 Rapid Antigen-Detection Test for the Diagnosis of SARS-CoV-2 Infection
A prospective multi-center study conducted in Spain found that the PanbioTM COVID-19 Ag Rapid Test Device, which tests for SARS-CoV-2 using nasopharyngeal swabs, has an overall sensitivity of 91% and specificity of 99%. Among the 128 asymptomatic participants who had close contact with a COVID-19 patient, there was full concordance in the 31 (24%) who…
Self-Collected Oral Fluid Saliva Is Insensitive Compared With Nasal-Oropharyngeal Swabs in the Detection of Severe Acute Respiratory Syndrome Coronavirus 2 in Outpatients
A study of people with confirmed SARS-CoV-2 infection suggests that self-collected oral fluid is significantly less sensitive for diagnosis than self-collected nasal-oropharyngeal specimens, especially after five days have passed since the onset of symptoms. Of the samples, which were matched by patient, 60 were concordantly negative, 45 concordantly positive, and 66 were discordant (63 nasal-OP…
February 17, 2021
Misinterpretation of Viral Load in COVID-19 Clinical Outcomes
Raw RT-PCR cycle threshold (Ct) values may lead to misinterpretation of the total viral burden, according to a study comparing tracheal aspirate (TA) with nasopharyngeal swab (NPS) samples in critically ill COVID-19 patients (n=138). The authors found that in general, TA samples had more total viral RNA than NPS samples, even though there was no…
February 16, 2021
The Usefulness Of SARS-CoV-2 Test-Positive Proportion As A Surveillance Tool
The test-positive proportion (TPP), the proportion of tested individuals who have tested positive, may be informative in predicting trends in COVID-19 incidence. The TPP strongly correlated with incidence in simulation results, as long as testing resources were sufficient to cover symptomatic and asymptomatic testing up to 35 days. However, the correlation between TPP and incidence…
Age- and Sex-Associated Variations in the Sensitivity of Serological Tests Among Individuals Infected With SARS-CoV-2
Antibodies against SARS-CoV-2 were detected in 75% (365 of 486) of patients in a University of California health system with PCR-confirmed SARS-CoV-2 who subsequently underwent antibody testing a median of 34 days later (IQR: 3-64 days). Seropositivity was associated with a longer delay between PCR and antibody testing, with sensitivity reaching 75% at 112 days…
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