What Is The Coronavirus (Covid-19) Antibody Test?

The tests popularly known so far are involved in detecting the presence of viral infection and diagnosing COVID-19. However, the coronavirus (COVID-19) antibody test determines whether you had COVID-19 in the past and now have antibodies against the virus. Let us understand what coronavirus (COVID-19) antibody test is.

What Is The Coronavirus (Covid-19) Antibody Test?

There is a lot of eagerness to know about the antibody testing, also called serology testing. The eligibility of the test may vary, depending on the availability of the tests. This test is done to identify the presence of antibodies or the response of immune cells against the virus causing COVID-19.

This is a blood test and a blood sample is drawn from a vein in the arm. The sample is then tested to identify antibodies against the virus. Antibodies are the protective proteins that your body produces in response to the infection, which is crucial for fighting off and clearing out the virus.1 The antibodies get attached to the antigens of the virus and remove them from the body, which is when the infection is said to be cured.

What Does Coronavirus (Covid-19) Antibody Test Detect?

The antibody test shows if you had the previous infection with the virus. In this case, an antibody test for COVID-19 will tell you if you had been infected with COVID-19 in the past. As the antibody test detects the presence of proteins in response to the infection occurred in the past, it is useful to detect past infections. Depending on when a person was infected and the timing when the test was done, the antibody test may not be able to detect antibodies in a person who is having a current infection with COVID-19.2

The antibody test should not be used to diagnose a person for any current infection. To check for current infection, a viral test that detects the presence of the virus from the throat or nasal swabs must be done.

What Does Coronavirus (Covid-19) Antibody Test Results Indicate?

It is necessary to know what the coronavirus (COVID-19) antibody test results mean. The results may be identified as you being tested positive or negative.

A positive coronavirus (COVID-19) antibody test result means:

  • You have antibodies that have likely resulted from infection with COVID-19 virus or possibly a related coronavirus. It is not clear whether the antibodies can offer protection or immunity against the virus, which means it is not clear whether you can get the infection again or not.
  • If you do not have any symptoms, you probably do not have an active infection and follow-up may not be needed. However, if you have symptoms of the novel coronavirus disease and meet the testing guidelines, you may need an additional test to detect the presence of the virus. As a coronavirus (COVID-19) antibody test cannot detect an active infection, you will need a viral test done using respiratory samples.
  • In some cases, it is possible that you may test positive for the antibodies but you may not have or never had symptoms of COVID-19. This is an infection without symptoms, called asymptomatic infection.

A negative coronavirus (COVID-19) antibody test result means :

  • You did not have a previous infection with the COVID-19 virus. However, you could have a present infection or can get the infection on getting exposed to an infected person.
  • The antibodies take 1 to 3 weeks to show up after the infection occurs, so if you have a current infection, you are likely to spread it to others. The period for showing up the antibodies defers from person to person, some may take longer while some may not even develop the antibodies.2
  • For any symptoms or if you meet the guidelines for testing, you may need a viral test to detect any active current infection.

What Is The Use Of The Coronavirus (Covid-19) Antibody Test?

The coronavirus (COVID-19) antibody test assesses the development of an immune response to the virus in patients by detecting the presence of 3 types of antibodies, which are IgG, IgM, and IgA, which the body produces in response to the infection.3 These tests are not useful to detect the virus or diagnose in early infection, as the antibodies need time to develop against the respective antigens. These antibodies are less useful to monitor the immediate response and hence the coronavirus (COVID-19) antibody test is not useful to detect or screen active, early infections. However, as the viral genome is not detectable once the patient recovers from COVID-19 infection, the status of the patient regarding their ability to contract or resist the infection may depend on the presence of antibodies against the infection.3

The coronavirus (COVID-19) antibody test is an important and useful test as it helps document the presence of antibodies produced by the immune system against the COVID-19 virus. The test is useful to understand the presence of past COVID-19 infection in a person, based on which further evaluation or action can be taken. The studies regarding the immune status of a previously infected person and the risk of re-infection are being studied based on such results.

The coronavirus (COVID-19) antibody test is useful:

  • To detect the immunity of an exposed population
  • To test the infection status of workforce segment
  • To monitor the spread of disease
  • To study the progression of the disease

This data can be useful to make educated decisions about quarantine and social distancing in a given area and can be used for risk stratification of other people. This is particularly useful for frontline workers like healthcare providers, police, firefighters, utility workers, and other essential workforce employees.3 The coronavirus (COVID-19) antibody test can also be useful for the surgeons and healthcare providers, to know if they have been exposed to the virus.

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