Rapid SARS-CoV-2 antigen detection assay in comparison with real-time RT-PCR assay for laboratory diagnosis of COVID-19 in Thailand
Chutikarn Chaimayo 1, Bualan Kaewnaphan 1, Nattaya Tanlieng 1, Niracha Athipanyasilp 1, Rujipas Sirijatuphat 2, Methee Chayakulkeeree 2, Nasikarn Angkasekwinai 2, Ruengpung Sutthent 1, Nattawut Puangpunngam 3, Theerawoot Tharmviboonsri 4, Orawan Pongraweewan 5, Suebwong Chuthapisith 3, Yongyut Sirivatanauksorn 3, Wannee Kantakamalakul 1, Navin Horthongkham 6

Virol J 2020 Nov 13;17(1):177. doi: 10.1186/s12985-020-01452-5.
Abstract
Background: The Coronavirus disease 2019 (COVID-19) pandemic continues to spread across the world. Hence, there is an urgent need for rapid, simple, and accurate tests to diagnose severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Performance characteristics of the rapid SARS-CoV-2 antigen detection test should be evaluated and compared with the gold standard real-time reverse transcription-polymerase chain reaction (RT-PCR) test for diagnosis of COVID-19 cases.

Methods: The rapid SARS-CoV-2 antigen detection test, Standard™ Q COVID-19 Ag kit (SD Biosensor®, Republic of Korea), was compared with the real-time RT-PCR test, Allplex™ 2019-nCoV Assay (Seegene®, Korea) for detection of SARS-CoV-2 in respiratory specimens. Four hundred fifty-four respiratory samples (mainly nasopharyngeal and throat swabs) were obtained from COVID-19 suspected cases and contact individuals, including pre-operative patients at Siriraj Hospital, Bangkok, Thailand during March-May 2020.

Results: Of 454 respiratory samples, 60 (13.2%) were positive, and 394 (86.8%) were negative for SARS-CoV-2 RNA by real-time RT-PCR assay. The duration from onset to laboratory test in COVID-19 suspected cases and contact individuals ranged from 0 to 14 days with a median of 3 days. The rapid SARS-CoV-2 antigen detection test's sensitivity and specificity were 98.33% (95% CI, 91.06-99.96%) and 98.73% (95% CI, 97.06-99.59%), respectively. One false negative test result was from a sample with a high real-time RT-PCR cycle threshold (Ct), while five false positive test results were from specimens of pre-operative patients.

Conclusions: The rapid assay for SARS-CoV-2 antigen detection showed comparable sensitivity and specificity with the real-time RT-PCR assay. Thus, there is a potential use of this rapid and simple SARS-CoV-2 antigen detection test as a screening assay.

Keywords: COVID-19; RT-PCR; Rapid antigen; SARS-CoV-2; Thailand.

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