Explained: What is antibody test for COVID-19 and why is it important?

While India is set to begin antibody tests on people to identify more cases of COVID-19, a lot of doubts have risen on what is different about the antibody test when compared to the regular diagnostic testing that has been done so far.

Tests for viruses can be of two types: genetic and serological.

A genetic viral test, the one currently used to diagnose patients for COVID-19, can detect infections that are active, but not past ones.

This is done through observation of nasal or throat swabs.

On the other hand, an antibody test, which falls under the category of a serological viral test, can detect a previous viral infection and find out if the person had been asymptomatic.

Serological tests will allow doctors to determine if a person was previously infected with the virus — in this case, the coronavirus — based on the presence of antibodies in the blood.

Antibodies are produced by the immune system in one’s body when threatened by bacteria or viruses in order to kill the germs. These antibodies are present for quite a period of time after recovery from the infection.

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To neutralize a pathogen (bacteria or viruses), the antibody latches itself on to a unique form of protein on the pathogen’s surface, known as an antigen. These antigen molecules are used in serological tests to identify the presence of antibodies relevant to a specific infection.

In a serological test, if the relevant antibodies are present in a blood sample, these antibodies will latch on to the antigens placed next to them. These antibodies and antigens help identify the pathogen that had infected the human body.

Such tests are fairly cheap and can give results within a few minutes.

In order to trace more cases of coronavirus infections, experts claim it is necessary to identify through the serological test those who were previously infected by the virus and had recovered.