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. 2020 Jul 29;21(15):5380.
doi: 10.3390/ijms21155380.

A Rapid, Simple, Inexpensive, and Mobile Colorimetric Assay COVID-19-LAMP for Mass On-Site Screening of COVID-19

Franklin Wang-Ngai Chow  1 , Tony Tat-Yin Chan  1 , Anthony Raymond Tam  2 , Suhui Zhao  1 , Weiming Yao  1 , Joshua Fung  1 , Flora Ka-Kei Cheng  1 , George Chi-Shing Lo  1 , Stella Chu  1 , Kam Leng Aw-Yong  1 , James Yat-Man Tang  1 , Chi-Ching Tsang  1 , Hayes Kam-Hei Luk  1 , Antonio Cheuk-Pui Wong  1 , Kenneth Sze-Ming Li  1 , Longchao Zhu  1 , Zirong He  1 , Emily Wan Ting Tam  3 , Tom Wai-Hin Chung  4 , Sally Cheuk Ying Wong  5 , Tak-Lun Que  6 , Kitty Sau-Chun Fung  7 , David Christopher Lung  5 , Alan Ka-Lun Wu  8 , Ivan Fan-Ngai Hung  9 , Patrick Chiu-Yat Woo  1   10 , Susanna Kar-Pui Lau  1   10
Affiliations

A Rapid, Simple, Inexpensive, and Mobile Colorimetric Assay COVID-19-LAMP for Mass On-Site Screening of COVID-19

Franklin Wang-Ngai Chow et al. Int J Mol Sci. .

Abstract

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.

Keywords: COVID-19; RT-LAMP; SARS-CoV-2; diagnosis; mass screening; mobile Diagnostic; on-site screening.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Illustration of a small van-sized mobile COVID-19-LAMP diagnostic unit. A drawn-to-scale layout of a van-sized mobile COVID-19-LAMP diagnostic unit, with sample processing and LAMP reactions compartments have been illustrated. A cargo van/lorry can be modified quickly to become a mobile diagnostic unit for rapid deployment in any region.
Figure 2
Figure 2
Box and whisker plot of COVID-19-LAMP results. The COVID-19-LAMP results of each SARS-CoV-2 qRT-PCR positive samples have been illustrated in the box and whisker plot at (A): 30 min, (B): 60 min, (C): 90 min with corresponding qRT-PCR Ct values of samples.
Figure 3
Figure 3
COVID-19-LAMP evaluation profile. SARS-CoV-2 qRT-PCR positive and negative respiratory samples are used for evaluation of COVID-19-LAMP.
See this image and copyright information in PMC

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