Understanding the Covid-19 tests

Understanding the Covid-19 tests

There are generally two types of tests being used currently to detect Covid-19 infections.

The first type of test looks for the presence of the virus in the body. It is called rt-PCR test (real time polymerase chain reaction). It can be used in the early phase of the infection to detect whether the virus is in the body or not. This is a swab test of the nose and throat. A positive result is diagnostic of a Covid-19 infection. A negative result means there is no virus presence in the body. However, this is also dependent on how the swab is done. There is still a small chance that the area swabbed was free of the virus despite it being present elsewhere. This is the sensitivity rate of the test. No test is 100% sensitive.

The second type of test looks for the antibody response to the Covid-19 virus. Since these antibodies take some time to appear in the body even after the virus is present, this test may not pick up an infection if it is used too early. This is called a false negative. A repeat test after 7 – 10 days is recommended. This is a blood test.

There are two types of antibodies that can be detected in the body. IgM appears earlier than IgG, which can remain for a long time even after recovery from the infection. Thus, a positive test for IgG does not necessarily mean the infection or virus is still in your body. It unsure, it is best to get your doctor to interpret the result for you.

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