OVERVIEW
INTENDED USE

COVID-19 IgG/IgM Rapid Test Kit (Whole Blood/Serum/Plasma) is a solid phase immunochromatographic assay for the rapid, qualitative and differential detection of IgG and IgM antibodies to 2019 Novel Coronavirus in human whole blood, serum or plasma. This test provides only a preliminary test result. Therefore, any reactive specimen with the COVID-19 IgG/IgM Rapid Test kit (Whole Blood/Serum/Plasma) must be confirmed with alternative testing method(s) and clinical findings.

INTRODUCTION

Coronaviruses are enveloped RNA viruses that are distributed broadly among humans, other mammals, and birds and that cause respiratory, enteric, hepatic, and neurologic diseases. Seven coronavirus species are known to cause human disease. Four viruses - 229E, OC43, NL63, and HKU1 - are prevalent and typically cause common cold symptoms in immunocompetent individuals. The three other strains - severe acute respiratory syndrome coronavirus (SARS -CoV), Middle East respiratory syndrome coronavirus (MERS -CoV) and 2019 Novel Coronavirus (COVID-19) are zoonotic in origin and have been linked to sometimes fatal illness. IgG and IgM antibodies to 2019 Novel Coronavirus can be detected with 2 -3 weeks after exposure. IgG remains positive, but the antibody level drops overtime.

Diagram by: Akil Hamsath - Washington State University

PRINCIPLE

The COVID-19 IgG/IgM Rapid Test kit (Whole Blood/Serum/Plasma) is a lateral flow immunochromatographic assay. The test uses anti-human IgM antibody (test line IgM) , anti-human IgG (test line IgG) and goat anti-rabbit IgG (control line C) immobilized on a nitrocellulose strip. The burgundy colored conjugate pad contains colloidal gold conjugated to recombinant COVID-19 anti-gens conjugated with colloid gold (COVID-19 conjugates) and rabbit IgG-gold conjugates. When a specimen followed by assay buffer is added to the sample well, IgM &/or IgG antibodies if present, will bind to COVID-19 conjugates making antigen antibodies complex. This complex migrates through nitrocellulose membrane by capillary action. When the complex meets the line of the corresponding immobilized antibody (anti-human IgM &/or anti-human IgG) the complex is trapped forming a burgundy colored band which confirms a reactive test result. Absence of a colored band in the test region indicates a non-reactive test result. The test contains an internal control (C band) which should exhibit a burgundy colored band of the immunocomplex goat anti rabbit IgG/rabbit-gold conjugate regardless of the color development on any of the test bands. Otherwise, the test result is invalid and the specimen must be retested with another device.

TEST PROCEDURE – FOR SERUM OR PLASMA SPECIMEN:

Allow test kit, specimen, buffer and/or controls to equilibrate to room temperature (15-30°C) prior to testing.

1. Remove the test strip/cassette from the sealed foil pouch and use it as soon as possible. Best results will be obtained if the assay is performed within one hour.​​

2. Place the test kit on a clean and level surface.​​​

3. Strip: Add 2uL of serum/plasma to the sample pad (purple place with Colloidal gold) of the test strip then add 2 drops (about 60 μL) of sample buffer to the buffer pad (top of the strip) immediately.

Cassette: Add 2uL of serum/plasma to the specimen well (A) of the test cassette, then add 2 drops (about 60 μL) of sample buffer to the buffer well (B) immediately.​

3. Wait for the colored line(s) to appear. The result should be read at 10 minutes. Positive results may be visible as soon as 2 minutes. Do not interpret the result after 15 minutes.​

TEST PROCEDURE – FOR WHOLE BLOOD SPECIMEN:

Allow test kit, specimen, buffer and/or controls to equilibrate to room temperature (15-30°C) prior to testing.

1. Remove the test strip/cassette from the sealed foil pouch and use it as soon as possible. Best results will be obtained if the assay is performed within one hour.​​

2. Place the test kit on a clean and level surface.​​​

3. Strip: Add 4uL of whole blood to the sample pad (purple place with Colloidal gold) of the test strip then add 2 drops (about 60 μL) of sample buffer to the buffer pad (top of the strip) immediately.

Cassette: Add 4uL of whole blood to the specimen well (A) of the test cassette, then add 2 drops (about 60 μL) of sample buffer to the buffer well (B) immediately.​

3. Wait for the colored line(s) to appear. The result should be read at 10 minutes. Positive results may be visible as soon as 2 minutes. Do not interpret the result after 15 minutes.​

INTERPRETATION OF RESULTS

NEGATIVE

If only C band is present, the absence of any burgundy color in both T bands (IgG and IgM) indicates that no anti-COVID-19 antibodies are detected in the specimen.  The result is negative.

 

IgM POSITIVE

In addition to the presence of C band, if only IgM band is developed, the test indicates for the presence of COVID-19 IgM antibodies in the specimen.  The result is COVID-19 IgM positive.

 

IgG POSITIVE

In addition to the presence of C band, if only IgG band is developed, the test indicates for the presence of COVID-19 IgG antibodies in the specimen.  The result is COVID-19 IgG positive.

 

IgG and IgM POSITIVE

In addition to the presence of C band, if both IgG and IgM bands are developed, the test indicates the presence of both COVID-19 IgG and COVID-19 IgM antibodies in the specimen.  The result is COVID-19 IgG and COVID-19 IgM positive.

 

INVALID

If the C line fails to appear, ignore the test result. Insufficient specimen volume or incorrect procedural techniques are the most likely reasons for the failure. Review the procedure and repeat the test if possible.

LIMITATIONS
  1. Use fresh samples whenever possible. Frozen and thawed samples (especially repeatedly) contain particles that can block the membrane. This slows the flow of reagents and can lead to high background color, making the interpretation of results difficult.

  2. Optimal assay performance requires strict adherence to the assay procedure described in this insert sheet. Deviations may lead to aberrant results.

  3. A negative result for an individual subject indicates absence of detectable anti-COVID-19 antibodies. However, a negative test result does not preclude the possibility of exposure to or infection with COVID-19.

  4. A negative result can occur if the quantity of the anti-COVID-19 antibodies present in the specimen is below the detection limits of the assay, or the antibodies that are detected are not present during the stage of disease in which a sample is collected.

  5. Some specimens containing unusually high titer of heterophile antibodies or rheumatoid factor may affect expected results.

  6. As with all diagnostic tests, a definitive clinical diagnosis should not be based on the result of a single test, but should only be made by the physician after all clinical and laboratory findings have been evaluated.

  7. Relative Sensitivity: 91.8%, Relative Specificity: 96.4%, Overall Agreement: 95%

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