There are different tests for the diagnosis of the COVID-19 on the market. Then, many questions may arise about which would be the most suitable, how precise each one is, and what the technical terms mean. For clarifications, find bellow a description of the three most common tests – IgM, IgG and, PCR.
IgM and IgG Rapid Tests are Serological Tests
With a little needle prick on the fingertip, a small blood sample is collected and applied to a strip to detect IgG and IgM antibodies produced by the human body to defend itself against the coronavirus. The test result takes about 10 to 15 minutes. No laboratory analysis is required.
Rapid tests do not detect the virus during the first days of infection or symptoms. For precision, the test should be performed, at least, 10 days after the first symptom because the organism takes a minimum period to develop antibodies after exposure to the virus.
Note: People with a positive response to IgM are considered suspected cases and must be tested with PCR tests to confirm the result.
PCR Tests are Molecular Tests
PCR tests identify the virus in the organism through the analysis of specimens collected from the patient’s throat and nose – know as “swab test”. Laboratory analysis is required and the result takes, at least, 12 hours.
These tests are indicated for people without symptoms, who tested IgM-positive in the rapid test, and also with symptoms; that is, during the active phase of the disease or with high viral load.
Relevance of the Tests
In general, the results for IgM and IgG tests must be analyzed as a whole and the patient’s symptoms and history must be considered. This data combination is the key to guide the responsible physician through the actions to be taken.
The tests help to protect everyone. People identified as suspected or confirmed cases must be isolated to prevent contamination of colleagues and family members and must be monitored by health care professionals. All the others must continue to follow hygiene and social distancing measures.
Reinforces Paulo Lima, Vale physician