Evaluation of the INDICAID COVID-19 Rapid Antigen Test in Symptomatic Populations and Asymptomatic Community Testing

• Published in: Microbiology spectrum Vol. 9; no. 1; p. e0034221
• Main Authors: Chiu, Ricky Y. T., Kojima, Noah, Mosley, Garrett L., Cheng, Kwok Kin, Pereira, David Y., Brobeck, Matthew, Chan, Tsun Leung, Zee, Jonpaul Sze-Tsing, Kittur, Harsha, Chung, Cheuk Yiu Tenny, Tsang, Eric, Maran, Kajal, Yung, Raymond Wai-Hung, Leung, Alex Chin-Pang, Siu, Ryan Ho-Ping, Ng, Jessica Pui-Ling, Choi, Tsz Hei, Fung, Mei Wai, Chan, Wai Sing, Lam, Ho Yin, Lee, Koon Hung, Parkin, Sean, Chao, Felix C., Ho, Stephen Ka-Nung, Marshak, Daniel R., Ma, Edmond Shiu-Kwan, Klausner, Jeffrey D.
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 03.09.2021
• Subjects: Adult; antigen; Antigens, Viral - analysis; Asymptomatic Diseases; asymptomatic screening; Clinical Laboratory Techniques - methods; COVID-19; COVID-19 - diagnosis; COVID-19 - immunology; COVID-19 Testing - methods; False Negative Reactions; False Positive Reactions; Female; Hong Kong; Humans; Male; Mass Screening - methods; Middle Aged; Pandemics; Polymerase Chain Reaction; Public Health; rapid; Research Article; SARS-CoV-2; SARS-CoV-2 - genetics; SARS-CoV-2 - isolation & purification; Sensitivity and Specificity; Specimen Handling; Time Factors; Young Adult; Hong Kong; COVID-19; SARS-CoV-2; USA; Hong Kong; asymptomatic screening; rapid; antigen
• ISSN: 2165-0497; 2165-0497
• DOI: 10.1128/Spectrum.00342-21

Laboratory-based RT-PCR, the current gold standard for COVID-19 testing, can require a turnaround time of 24 to 48 h from sample collection to result. The delayed time to result limits the effectiveness of centralized RT-PCR testing to reduce transmission and stem potential outbreaks. As the COVID-19 pandemic progresses, there is an increasing need for rapid, accessible assays for SARS-CoV-2 detection. We present a clinical evaluation and real-world implementation of the INDICAID COVID-19 rapid antigen test (INDICAID rapid test). A multisite clinical evaluation of the INDICAID rapid test using prospectively collected nasal (bilateral anterior) swab samples from symptomatic subjects was performed. The INDICAID rapid test demonstrated a positive percent agreement (PPA) and negative percent agreement (NPA) of 85.3% (95% confidence interval [95% CI], 75.6% to 91.6%) and 94.9% (95% CI, 91.6% to 96.9%), respectively, compared to laboratory-based reverse transcriptase PCR (RT-PCR) using nasal specimens. The INDICAID rapid test was then implemented at COVID-19 outbreak screening centers in Hong Kong as part of a testing algorithm (termed “dual-track”) to screen asymptomatic individuals for prioritization for confirmatory RT-PCR testing. In one approach, preliminary positive INDICAID rapid test results triggered expedited processing for laboratory-based RT-PCR, reducing the average time to confirmatory result from 10.85 h to 7.0 h. In a second approach, preliminary positive results triggered subsequent testing with an onsite rapid RT-PCR, reducing the average time to confirmatory result to 0.84 h. In 22,994 asymptomatic patients, the INDICAID rapid test demonstrated a PPA of 84.2% (95% CI, 69.6% to 92.6%) and an NPA of 99.9% (95% CI, 99.9% to 100%) compared to laboratory-based RT-PCR using combined nasal/oropharyngeal specimens. The INDICAID rapid test has excellent performance compared to laboratory-based RT-PCR testing and, when used in tandem with RT-PCR, reduces the time to confirmatory positive result. IMPORTANCE Laboratory-based RT-PCR, the current gold standard for COVID-19 testing, can require a turnaround time of 24 to 48 h from sample collection to result. The delayed time to result limits the effectiveness of centralized RT-PCR testing to reduce transmission and stem potential outbreaks. To address this, we conducted a thorough evaluation of the INDICAID COVID-19 rapid antigen test, a 20-minute rapid antigen test, in both symptomatic and asymptomatic populations. The INDICAID rapid test demonstrated high sensitivity and specificity with RT-PCR as the comparator method. A dual-track testing algorithm was also evaluated utilizing the INDICAID rapid test to screen for preliminary positive patients, whose samples were then prioritized for RT-PCR testing. The dual-track method demonstrated significant improvements in expediting the reporting of positive RT-PCR test results compared to standard RT-PCR testing without prioritization, offering an improved strategy for community testing and controlling SARS-CoV-2 outbreaks.