What are they?
These are tests that detect the presence in the serum (a part of the blood) of antibodies (Immunoglobulins, Ig) produced by the immune system to defend itself from what comes from outside (Antigens), and that can be a threat, such as the SARS-CoV-2 and therefore indicate whether or not a subject has come into contact with an infectious agent.
The quantitative serological test with CLIA method is done through the CLIA method.
The quantitative serological test with CLIA method is performed through a venous sampling from the arm performed by a nurse and a subsequent laboratory analysis of the blood tube with CLIA method carried out at the authorized laboratory of the MultiMedica Group: the Polo Scientifico Tecnologico of Milan. These tests, in addition to detecting the presence of IgM and IgG antibodies, also measure the amount of IgG.
The antibodies called “IgM” are produced in the initial phase of the infection, are found in the blood starting from 3 or 6 days after the appearance of symptoms and then tend to disappear within a few weeks. The other antibodies, called “IgG”, are produced later and are found in the blood starting from a couple of weeks after the onset of symptoms (but may appear even earlier) and should then remain for a long time.
The serological test can provide the following results:
- IgM and IgG negative: there has been no infection, or the exposure to the pathogen occurred too short time ago and a detectable immune reaction has not yet been developed, or the level of antibodies produced is too low to be detected by the test;
- only IgM positive: exposure to the antigen is very recent.
- IgM and IgG positive: the infection is ongoing and has been contracted recently;
- only IgG positive: the infection has been there but it is not recent.
Depending on the results, other tests may be needed to arrive at an accurate diagnosis.