Background The outbreak of coronavirus disease 2019 (COVID-19) began in December 2019 and continues to spread worldwide. Rapid and accurate identification of suspected cases is critical in slowing spread of the virus that causes the disease. We aimed to highlight discrepancies in the various criteria used by international agencies and highly impacted individual countries around the world. Methods We reviewed the criteria for identifying a suspected case of COVID-19 used by two international public health agencies and 10 countries across Asia, Europe, and North America. The criteria included information on the clinical causes of illness and epidemiological risk factors. Non-English language guidelines were translated into English by a co-author who is fluent in that particular language. Results Although most criteria are modifications of World Health Organization recommendations, the specific clinical features and epidemiological risks for triggering evaluation of patients with suspected COVID-19 differed widely among countries. The rationale for these differences may be related to each country’s resources, politics, experience with previous outbreaks or pandemics, health insurance system, COVID-19 outbreak severity, and other undetermined factors. Conclusion We found no consensus regarding the best diagnostic criteria for identifying a suspected case of COVID-19.
Many assays aimed to test the inhibitory effects of synthetic molecules, and naturally occurring products on the neuraminidase activity exploit the hydrolysis of 2'-O-(4-methylumbelliferyl)-N-acetylneuraminic acid (4-MUNANA). The amount of the released product, 4-methylumbelliferone (4-MU), is then measured fluorimetrically. The authors attempted an analysis of the inhibitory properties of 35 naturally occurring flavonoids on neuraminidase N3, where only 29 of them were sufficiently soluble in the assay medium. During the analysis, the authors noticed a strong quenching effect due to the test compounds on the fluorescence of 4-MU. The quenching constants for the flavonoids were determined according to the Stern-Volmer approach. The extent of fluorescence reduction due to quenching and the magnitude of the fluorescence reduction measured in the inhibition assays were comparable: for 11 of 29 compounds, the two values were found to be coincident within the experimental uncertainty. These data were statistically analyzed for correlation by calculating the pertinent Pearson correlation coefficient. Inhibition and quenching were found to be positively correlated (r = 0.71, p(uncorr) = 1.5 × 10(-5)), and the correlation was maintained for the whole set of tested compounds. Altogether, the collected data imply that all of the tested flavonoids could produce false-positive results in the neuraminidase inhibition assay using 4-MUNANA as a substrate.
Background: The outbreak of coronavirus disease 2019 (COVID-19) began in December 2019 and is spreading rapidly. Rapid and accurate identification of suspected cases is critical in suppressing viral spread. We aimed to highlight the discrepancies in the varying criteria used by international agencies and highly impacted individual countries worldwide.Methods: The criteria from two international agencies and ten countries across Asia, Europe, and North America were reviewed. Each included information on the clinical causes of illness and epidemiology risk factors. Non-English language guidelines were translated into English by one of the co-authors who was fluent in that language. Results: Although the majority of criteria are modified from the World Health Organization recommendations, the specific clinical features and epidemiological risks for triggering evaluation of COVID-19 in suspected patients differed widely among nations. The rationale for these differences may be linked to each individual country’s resources, politics, experience with previous outbreaks or pandemics, health insurance systems, severity of the COVID-19 situation, and other undetermined factors. Conclusion: There was no consensus on the single best criteria for identifying a suspected case of COVID-19.
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