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.

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Delayed Influenza Treatment in Children With False-Negative Rapid Antigen Test: A Retrospective Single-Center Study in Korea 2016-2019

Background: We aimed to examine the delay in antiviral initiation in rapid antigen test (RAT) false-negative children with influenza virus infection and to explore the clinical outcomes. We additionally conducted a medical cost-benefit analysis.
Methods: This single-center, retrospective study included children (aged < 10 years) with influenza-like illness (ILI), hospitalized after presenting to the emergency department during three influenza seasons (2016-2019). RAT-false-negativity was defined as RAT-negative and polymerase chain reaction-positive cases. The turnaround time to antiviral treatment (TAT) was from the time when RAT was prescribed to the time when the antiviral was administered. The medical cost analysis by scenarios was also performed.
Results: A total of 1,430 patients were included, 7.5% were RAT-positive (n = 107) and 2.4% were RAT-false-negative (n = 20). The median TAT of RAT-false-negative patients was 52.8 hours, significantly longer than that of 4 hours in RAT-positive patients (19.2-100.1, P < 0.001). In the multivariable analysis, TAT of ≥ 24 hours was associated with a risk of severe influenza infection and the need for mechanical ventilation (odds ratio [OR], 6.8, P = 0.009 and OR, 16.2, P = 0.033, respectively). The medical cost varied from $11.7-187.3/ILI patient.
Conclusion: Antiviral initiation was delayed in RAT-false-negative patients. Our findings support the guideline that children with influenza, suspected of having severe or progressive infection, should be treated immediately.

Rapid Antigen Test Combine with Nucleic Acid Detection: A Better Strategy for COVID-19 Screening at Points of Entry

The coronavirus disease 2019 (COVID-19) pandemic has imposed an enormous disease burden worldwide, and the Delta variant now has become dominant in 53 countries. Recently published studies have shown that during periods of high viral load, rapid antigen tests (RAT) yield similar results to reverse transcriptase-polymerase chain reaction (RT-PCR) tests, and when used in serial screening (e.g., every three days), it has a high sensitivity.

SARS-CoV-2 Antigen Rapid Test Kit

CoV2Ag-1 UnScience 1T 8 EUR

SARS-CoV-2 Antigen Rapid Test Kit

CoV2Ag-25 UnScience 25T/kit 35 EUR

SARS-CoV-2 Rapid Antigen Test Nasal

9901-NCOV-03G Roche Diagnostics 25 Tests/Kit 94 EUR

Human Streptococcus Pneumoniae (SP) Antigen Rapid Test Kit

abx092096-20tests Abbexa 20 tests 398 EUR

NDV rapid test kit

RG15-03 Bionote 1 box 139.05 EUR

IBD rapid test strip

RG15-04 Bionote 10 boxes 148 EUR

Rabies rapid test strip

RG18-01 Bionote 10 boxes 151.92 EUR

Melamine Rapid Test Kit

abx092011-50tests Abbexa 50 tests 370 EUR

Accu-Tell COVID-19 IgG/IgM Rapid Test

GEN-B352-20tests Accu test 20 tests 236 EUR

Accu-Tell COVID-19 IgG/IgM Rapid Test

GEN-B352-40tests Accu test 40 tests 321 EUR

Avian Influenza Virus Antigen Rapid Test Kit (Colloidal gold)

abx092015-40tests Abbexa 40 tests 432 EUR

Newcastle Disease Virus Antigen Rapid Test Kit (Colloidal gold)

abx092016-40tests Abbexa 40 tests 432 EUR

Human Chlamydia Trachomatis Antigen Rapid Test Kit (Colloidal gold)

abx092049-20tests Abbexa 20 tests 230 EUR

Coronavirus (SARS-Cov-2) Antigen Rapid Test Device (Saliva)

IOV87952 INVBIO 20T/kit 39 EUR

Rapid Leishmania Ab Test Kit

RB2104 Bionote 1 box 127 EUR

Rapid PED Ag Test Kit

RG14-01 Bionote 1 box 159.9 EUR

Melamine (MEL) Rapid Test Kit

abx092057-50tests Abbexa 50 tests 370 EUR

Clenbuterol (CLE) Rapid Test Kit

abx092058-50tests Abbexa 50 tests 244 EUR

Ractopamine (RAC) Rapid Test Kit

abx092059-50tests Abbexa 50 tests 244 EUR

Salbutamol (SAL) Rapid Test Kit

abx092060-50tests Abbexa 50 tests 244 EUR

Tetracycline (TCs) Rapid Test Kit

abx092063-50tests Abbexa 50 tests 398 EUR

Sulfonamides (Sas) Rapid Test Kit

abx092064-40tests Abbexa 40 tests 398 EUR

Quinolones (QNs) Rapid Test Kit

abx092065-40tests Abbexa 40 tests 398 EUR

Ciprofloxacin (CPFX) Rapid Test Kit

abx092066-50tests Abbexa 50 tests 398 EUR

Quinolones (QNs) Rapid Test Kit

abx092067-40tests Abbexa 40 tests 398 EUR

Brucella Antibody Rapid Test Kit

abx092069-40tests Abbexa 40 tests 356 EUR

Procalcitonin rapid test (Colloidal Gold)

abx095264-80Units Abbexa 80 Units 954 EUR

Avian Influenza H5 Virus Antigen Rapid Test Kit (Colloidal gold)

abx092014-40tests Abbexa 40 tests 488 EUR

Avian Influenza H7 Virus Antigen Rapid Test Kit (Colloidal gold)

abx092017-40tests Abbexa 40 tests 432 EUR

Anigen Rapid FIV Ab Test Kit

RB22-01-DD Bionote 10 tests/Kit 129.8 EUR

Rapid Bovine Brucella Ab Test Kit

RB23-01-DD Bionote 1 kit/10 tests 151.79 EUR

Rapid Bovine TB Ab Test Kit

RB23-02-DD Bionote 1 box 128.4 EUR

Rapid FMD NSP Ab Test Kit

RB28-02-DD Bionote 1 box 135.4 EUR

Ag rapid CDV Ag Test Kit

RG11-03 Bionote 1 box 138.2 EUR

Rapid TGE/PED Ag Test Kit

RG14-03 Bionote 1 box 240.85 EUR

Ag Rapid AIV Ag Test Kit

RG15-01 Bionote 1 box/30 tests 267 EUR

Ag Rapid H5AIV Ag test kit

RG15-05 Bionote 1 box 463 EUR

Clenbuterol Rapid Test Kit (Colloidal gold)

abx092040-50tests Abbexa 50 tests 272 EUR

Ractopamine Rapid Test Kit (Colloidal gold)

abx092042-50tests Abbexa 50 tests 300 EUR

Salbutamol Rapid Test Kit (Colloidal gold)

abx092043-50tests Abbexa 50 tests 342 EUR

In this perspective, we recommend RT-PCR combined with RAT at points of entry: (i) RAT can be added to the detection phase at ports of entry to detect asymptomatic infections as early as possible; (ii) RAT can be added to post-entry quarantine every three days or less to reduce the rate of missed detection in later quarantine; (iii) Adding regular RAT to regular PCR testing for key airport personnel to prevent cross-infection and conduct closed-off management.

In the face of sporadic Delta variant outbreaks, the combination of the two could help rapid triage and management of suspected populations at an early stage and thus contain the outbreak more quickly and effectively. We also discuss the issue of whether the current antigen detection reagents can cope with various SARS-CoV-2 variants.

Multicenter Technical Validation of 30 Rapid Antigen Tests for the Detection of SARS-CoV-2 (VALIDATE)


During COVID19 pandemic, SARS-CoV-2 rapid antigen tests (RATs) were marketed with minimal or no performance data. We aimed at closing this gap by determining technical sensitivities and specificities of 30 RATs prior to market release. We developed a standardized technical validation protocol and assessed 30 RATs across four diagnostic laboratories. RATs were tested in parallel using the Standard Q (SD Biosensor/Roche) assay as internal reference. We used left-over universal transport/optimum media from nasopharyngeal swabs of 200 SARS-CoV-2 PCR-negative and 100 PCR-positive tested patients.

Transport media was mixed with assay buffer and applied to RATs according to manufacturer instructions. Sensitivities were determined according to viral loads. Specificity of at least 99% and sensitivity of 95%, 90%, and 80% had to be reached for 107, 106, 105 virus copies/mL, respectively. Sensitivities ranged from 43.5% to 98.6%, 62.3% to 100%, and 66.7% to 100% at 105, 106, 107 copies/mL, respectively. Automated assay readers such as ExDia or LumiraDx showed higher performances. Specificities ranged from 88.8% to 100%. Only 15 of 30 (50%) RATs passed our technical validation. Due to the high failure rate of 50%, mainly caused by lack of sensitivity, we recommend a thorough validation of RATs prior to market release.