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Int J Mol Sci ; 21(15)2020 Jul 29.
Article in English | MEDLINE | ID: covidwho-693630


To control the COVID-19 pandemic and prevent its resurgence in areas preparing for a return of economic activities, a method for a rapid, simple, and inexpensive point-of-care diagnosis and mass screening is urgently needed. We developed and evaluated a one-step colorimetric reverse-transcriptional loop-mediated isothermal amplification assay (COVID-19-LAMP) for detection of SARS-CoV-2, using SARS-CoV-2 isolate and respiratory samples from patients with COVID-19 (n = 223) and other respiratory virus infections (n = 143). The assay involves simple equipment and techniques and low cost, without the need for expensive qPCR machines, and the result, indicated by color change, is easily interpreted by naked eyes. COVID-19-LAMP can detect SARS-CoV-2 RNA with detection limit of 42 copies/reaction. Of 223 respiratory samples positive for SARS-CoV-2 by qRT-PCR, 212 and 219 were positive by COVID-19-LAMP at 60 and 90 min (sensitivities of 95.07% and 98.21%) respectively, with the highest sensitivities among nasopharyngeal swabs (96.88% and 98.96%), compared to sputum/deep throat saliva samples (94.03% and 97.02%), and throat swab samples (93.33% and 98.33%). None of the 143 samples with other respiratory viruses were positive by COVID-19-LAMP, showing 100% specificity. Samples with higher viral load showed shorter detection time, some as early as 30 min. This inexpensive, highly sensitive and specific COVID-19-LAMP assay can be useful for rapid deployment as mobile diagnostic units to resource-limiting areas for point-of-care diagnosis, and for unlimited high-throughput mass screening at borders to reduce cross-regional transmission.

Betacoronavirus/genetics , Colorimetry/methods , Coronavirus Infections/diagnosis , Mass Screening/economics , Pneumonia, Viral/diagnosis , RNA, Viral/analysis , Betacoronavirus/isolation & purification , Colorimetry/economics , Coronavirus Infections/virology , Humans , Limit of Detection , Nasopharynx/virology , Nucleic Acid Amplification Techniques/methods , Pandemics , Pneumonia, Viral/virology , Point-of-Care Systems , RNA, Viral/metabolism , Viral Load
J Am Coll Emerg Physicians Open ; 2020 Jun 20.
Article in English | MEDLINE | ID: covidwho-609415


Objectives: Little is known about the value of routine clinical assessment in identifying patients with coronavirus disease 2019 (COVID-19) in the emergency department (ED). We aimed to compare the exposure history, signs and symptoms, laboratory, and radiographic features of ED patients who tested positive and negative for COVID-19. Methods: This was a case-control study in seven EDs in Hong Kong from 20 January to 29 February 2020. Thirty-seven patients with laboratory-confirmed COVID-19 were age- and gender-matched to 111 controls. We compared the groups with univariate analysis and calculated the odds ratio (OR) of having COVID-19 for each characteristic that was significantly different between the groups with adjustment for age and presumed location of acquiring the infection. Results: There were no significant differences in patient characteristics and reported symptoms between the groups. A positive contact history within 14 days (adjusted OR 37.61, 95% CI 10.86-130.19), bilateral chest radiograph shadow (adjusted OR 13.19, 95% CI 4.66-37.35), having prior medical consultation (adjusted OR 7.43, 95% 2.89 -19.09), a lower white blood cell count (adjusted OR 1.30, 95% CI 1.11-1.51), and a lower platelet count (adjusted OR 1.07, 95% CI 1.01-1.12) were associated with a higher odds of COVID-19 separately. A higher neutrophil count was associated with a lower odds of COVID-19 (adjusted OR 0.77, 95% CI 0.65-0.91). Conclusion: This study highlights a number of clinical features that may be useful in identifying high-risk patients for early testing and isolation while waiting for the test result. Further studies are warranted to verify the findings.This article is protected by copyright. All rights reserved.