After COVID-19 infection, the body develops IgM antibodies that mainly exist in the blood from a few hours to several days. IgM antibodies appear (symptomatic 3-5 days, asymptomatic 7 days) and gradually disappear earlier than IgG antibodies, while IgG antibodies are relatively longstanding.
COVID-19 IgM/IgG Antibody Screen Test utilizes indirect immunoassay to detect COVID-19 IgM/IgG antibodies qualitatively and selectively in serum or plasma or whole blood.
Updated United States Food and Drug Administration guidance issued on March 16, 2020, allows the distribution of this product for diagnostic use in laboratories or by healthcare workers at the point-of-care. The updated policy can be viewed by clicking
here. In April 2020, the FDA released a statement related to serological tests for antibodies responding to COVID-19 which can be found
here.
The rapid antibody test is limited in that it only provides a preliminary result. Any reactive specimen with the COVID-19 IgM/IgG Rapid test Cassette (whole blood/serum/plasma) must be confirmed with alternate testing method(s) and clinical findings. When IgG antibodies are present, it generally indicates past infection, but may also appear with recently-infected patients that are contagious. It is unknown how long IgM or IgG antibodies to SARS-CoV-2 will remain present in the body after infection or if they confer immunity to infection.
The COVID-19 IgM/IgG Antibody Screen Test is a qualitative membrane strip-based immunoassay for the detection of COVID-19 IgM/IgG antibody in serum or plasma or whole blood. According test procedure, anti-human IgM/IgG is immobilized in the test line region of the test. After a serum, plasma, or whole blood specimen is added in the specimen well, it reacts with COVID-19 antigen coated particles that have been applied to the specimen pad. This mixture migrates chromatographically along the test strip and interacts with the immobilized anti-human IgM/IgG. If the specimen contains COVID-19 IgM/IgG antibodies, a colored band will appear in the test line region indicating a positive result. If the specimen does not contain COVID-19 IgM/IgG antibodies, no colored band would appear in this region indicating a negative result. To serve as a procedural control, a colored band does always present at the control line region. It indicates that the test results are valid.