Detection of COVID-19 Virus : Rapid Serology Antibody Test

What is rapid serology antibody test?

Background

BioMedomics have developed and launched one of the world's first rapid test point-of-care lateral immunoassays to aid in the diagnosis of coronavirus infection. Both serology tests share a thing in common which is to detect the presence of antibodies, IgM and IgG. Rapid serology test uses the principle of capillary action to pull the sample across the strip into the test's detection zone. As the sample progresses across the detection zone, antibodies in the sample may bind to recombinant Covid antigens immobilized on the test membrane. This test use fresh sample and test it immediately instead of using the heat inactivated or other human inactivated human specimen such as blood, serum and plasma that have been incubated for some times.

What are the steps in rapid serology antibody test?

1. Collect 10 µL of blood/serum/plasma sample obtained by ventipuncture into blood collection tube or use fingertips blood.

2. Add the blood sample in sample well.

3. Add 2-3 drops of dilution buffer to the sample well.

4. Then, read the results after 10 minutes and no more than 15 minutes.

How to read the test result?

The test strip contain a colloidal gold-labeled recombinant novel coronavirus antigen and quality control antibody colloidal gold marker, two detection lines (G and M lines) and one quality control line (C) fixed on a nitrocellulose membrane. M is fixed with monoclonal anti-human IgM antibody for detecting the novel coronavirus IgM antibody G is fixed with monoclonal antihuman IgG antibody for detecting the novel coronavirus IgG antibody. The quality control antibody is fixed on the C line. A total of three detection line are possible, with the control (C) line appearing when sample has been flowed through the cassette. Following are the outcomes for this test:-

• If only the quality control line (C) appears and the detection lines G and M are not visible and the result is negative.
• If both the quality control line and the detection (C) and the detection line M appears, then the novel coronavirus IgM antibody has been detected and the result is positive for the IgM antibody.
• If both the quality control line (C) and the detection line G appears, then the novel coronavirus IgG antibody has been detected and the result is positive for the IgG antibody.
• If the quality control line (C) and both detection lines G and M appear, then the novel coronavirus IgG and IgM antibodies have been detected and the result is positive for both the IgG and IgM antibodies.

Although the rapid serology antibody test requires only a short time  and can facilitate in diagnosing COVID-19 infection, WHO does not currently recommends the use of this test and only suggest the test is used for research setting. In the statement created created by World Health Organization, they stated that the antibodies are produced over days to weeks after the infection. So, a diagnosis of COVID-19 infection based on antibody response will often be possible in the recovery phase, when many of the opportunities for clinical intervention of disease transmission have already passed. Other than that, antibody detection tests targeting COVID-19 can react with other pathogens and may give false results. 

However, WHO will continue to work with the research group and other agencies to develop and interpret data that might indicate specific areas where such tests can be useful for clinical management of cases and infection control.

Click for further explaination from WHO about rapid test method for the detection of COVID-19