Milestones

• The first FDA-approved COVID-19 rapid test kit
• Used by the U.S. Government

Key Advantages

• 15 minutes to get results
• Sample type: serum, plasma or whole blood
• Easy sample collection and operation in clinics, medical lab and hospitals
• IgM/IgG antibodies detection simultaneously if both are presented in specimen
• Incubation period: IgM reaches peak one week after infection and IgG in three weeks
• Accuracy up to 85% for positive detection
• To provide guidance for treatment and monitoring

Certifications & Standards

• FDA (USA)
• CE (Europe)
• TGA (Australia)
• ISO 13485
• Certificate for Exportation of Medical Products (China)

Production Capacity

500,000 tests per week

Test principle for Cellex qSARS-CoV-2 IgG/IgM Rapid Test

The Cellex qSARS-CoV-2 IgG/IgM Cassette Rapid Test is a lateral flow chromatographic immunoassay which can detect antibodies against the SARS-CoV-2 virus. The test cassette consists of: 1) a burgundy colored conjugate pad containing SARS-CoV-2 recombinant antigens conjugated with colloidal gold (SARS-CoV-2 conjugates) and rabbit IgG-gold conjugates; 2) a nitrocellulose membrane strip containing an IgG line (G Line) coated with anti-human IgG, an IgM line (M Line) coated with anti-human IgM, and the C line (C Line) coated with goat anti-rabbit IgG.

When an adequate volume of test specimen is dispensed into the sample well of the test cassette, the specimen migrates by capillary action along the cassette. The anti-SARS-CoV-2 virus IgG, if present in the specimen, will bind to the SARS-CoV-2 conjugates. The immunocomplex is then captured by the anti-human IgG line, forming a burgundy colored G line, indicating a SARS-CoV-2 virus IgG positive test result suggesting a secondary infection or previous infection.

IgM anti-SARS-CoV-2 virus, if present in the specimen, will bind to the SARS-CoV-2 conjugates. The immunocomplex is then captured by the anti-human IgM line, forming a burgundy colored M line, indicating a SARS-CoV-2 virus IgM positive test result suggesting a fresh primary infection.

If both G line and M line are visible, the test result suggests late primary or early secondary SARS-CoV-2 infection. Absence of both test bands (G and M) suggests a negative result.

The test contains an internal control (C line) which should exhibit a burgundy colored band of goat anti-rabbit IgG/rabbit IgG-gold conjugate immunocomplex regardless of the color development on any of the test bands (G and M). Otherwise, the test result is invalid and the specimen must be retested again.

Summary and explanation of the test

Coronaviruses (CoV) are a large family of viruses that cause illness ranging from the common cold to more severe diseases such as Middle East Respiratory Syndrome (MERS-CoV) and Severe Acute Respiratory Syndrome (SARS-CoV). SARS-CoV-2 is a new strain that has not been previously identified in humans. Coronaviruses are zoonotic, meaning they are transmitted between animals and people. Detailed investigations found that SARS-CoV was transmitted from civet cats to humans and MERS-CoV from dromedary camels to humans. Several known coronaviruses are circulating in animals that have not infected humans yet.

2019 Novel Coronavirus (SARS-CoV-2) is a virus (more specifically, a coronavirus) identified as the cause of an outbreak of respiratory illness first detected in Wuhan, China. Patients reported with SARS-CoV-2 viral infections had mild to severe respiratory illness with symptoms of: fever, cough, shortness of breath. There is an urgent need for rapid tests to manage the ongoing pandemic.

The qSARS-CoV-2 IgG/IgM Rapid Test is intended for rapid and qualitative detection of antibodies indicative of SARS-CoV-2 infection and used as an aid for diagnosis of SARS-CoV-2 infection.

Reagents and materials provided

Each kit includes:

• 25 test cassettes
• 1 bottle of sample buffer
• 25 transfer pipettes
• Leaflet with instructions for use

Material Required But Not Provided

• Transfer Pipette Set
• Timer
• Specimen Collection Containers
• Leaflet with instructions for use

Performance Characteristics

Clinical Performance

a) Testing of clinical specimens:

Ninety-eight (98) positive serum or plasma samples collected from individuals who were tested positive with an RT-PCR method for SARS-CoV-2 infection and were quarantined in a makeshift hospital were used in this study.

These patients, at the time of sample collected, exhibited mild or no clinical symptoms. These samples, along with 180 negative serum or plasma samples collected prior to September 2019, were coded and tested together with the qSARS-CoV-2 IgG/IgM Rapid Test. Of the 98 positive samples, ninety-one (91) were tested positive with IgG or IgM or both bands. Of the 180 negative samples, one hundred seventy four (174) were tested negative.

Another 30 samples were collected from hospitalized individuals who were clinically confirmed positive and exhibited severe symptoms. These samples, along with 70 negative serum or plasma samples collected prior to September 2019, were coded and tested together with the qSARS-CoV-2 IgG/IgM Rapid Test. Of the 30 positive samples, twenty-nine (29) were tested positive with IgG or IgM or both bands. Of the 70 negative samples, sixty-five (65) were tested negative.

Taken together, the qSARS-CoV-2 IgG/IgM Rapid Test had a sensitivity and specificity of 93.75% (95% CI: 88.06-97.26%) and 96.40% (95% CI: 92.26-97.78%), respectively.

b) Testing of Specimens that were RT-PCR negative but clinical positive:

Fifty (50) specimens collected from suspected patients who were RT-PCR negative but had history of being exposed and showed clinical symptoms consistent with an infection were tested with the qSARS-CoV-2 IgG/IgM Rapid Test. Of these samples, twelve (12) or 24% were positive with the test.

c) Whole blood specimens spiked with positive samples

Fifty negative whole blood samples were spiked with positive serum at 1:100. Another 50 whole blood specimens were spiked with negative serum at same dilution. These 100 specimens were coded and tested with the qSARS-CoV-2 IgG/IgM Rapid Test. All spiked samples were correctly identified by the test except for one of the negative samples, which was tested positive with the test.

Limit of Detection

Four positive samples were serially diluted, coded and tested in 20 replicates. The most diluted replicates at which 19 or 20 replicates were tested positive for these four samples were 1:60,000, 1:11,000, 1:2000, and 1:500, respectively.

Hook effects

Positive samples with titers up to 1:60,000 were found to be reactive when tested
with the qSARS-CoV-2 IgG/IgM Rapid Test.
Human IgG 8 mg/mL
Human IgM 0.4 mg/mL