In this video I want to talk about serological tests for covid-19 ( IgG & IgM Ab).
Antibodies are a crucial component of the immune system that is secreted by immune cells, and they are in 5 different classes, that the most important of them are IgG and IgM
IgG has a Y-like shape that each end of the fork contains an antigen-binding site that binds a specific antigen.
It's The main type of human antibody.
And The main factor of last lasting immunity, that produces immunity against a microbial agent in the next contamination.
It Binds to pathogens and neutralizes them.
IgG actives other immune system mechanisms such as Complement System, Antibody-dependent cell-mediated cytotoxicity (ADCC) and intracellular antibody-mediated proteolysis.
IgM
IgM is The first antibody that appears in the response to initial exposure to an antigen.
IgM has a 5 branches structure, containing antigen-binding sites in each fork, therefore it has 10 capacities to bind to antigens.
If we look at the corona antibody production chart, its shows these antibodies produce in the early second week of contamination, IgM reaches to peak in the third week, and then reduce in production.
IgG is produced in the second week, too, and reaches to peak in the fourth week, and it remains high at least for 3 months, and it's a reason for a booster dose of covid-19 vaccine to rise high this antibody again.
The sample for these tests is blood.
Because it takes at least a week after contamination to Covid-19 for the body to produce antibodies against it, this test is not used to diagnose this disease, but it can determine the phase of the disease.
The most important application of this test is in epidemiological studies to determine the immunity of a community against coronavirus, and also to determine the effectiveness of the Covid-19 vaccine.
And individual Evaluation of Immunity level against coronavirus. But as CDC recommendation, because different vaccines induce antibodies to specific viral protein targets, Antibody testing is not currently recommended to assess for immunity following COVID-19 vaccination. Therefore, If you want to do this test, you have to shore that the laboratory kit antibody is detectable for your vaccine brand.
Now let to interpret the results:
If IgG and IgM are both negative, shows that you're not infected with coronavirus, or you are in window period and the blood level of these antibodies are not detectable now.
If just IgM is positive, it shows you are in the early stage of first contamination to coronavirus.
If both of them are positive, it shows that you are in the Active phase of infection.
And if just IgG is positive, it shows you are in the late phase of disease, or you are re-infected to corona virus.
