The Covid-19 Antibody Test, Explained

A Covid-19 antibody test will quickly identify if you previously had this virus – regardless of your history of symptoms. In-home testing is a fast and convenient way to obtain your results without necessitating exposure to the virus.

What Is An Antibody Test?

In understanding the antibody test, let’s first discuss antibodies.

An antibody is a protein manufactured by white blood cells that protects against antigens (harmful bacteria, viruses, and other foreign substances). Antibodies bind to the intruder and eliminate it.

All antibodies defend against a specific antigen, meaning that an antibody for the flu is useless against another kind of illness. Therefore, you’re less likely to catch the same cold twice, since your body has raised a defense against that virus.

How does an antibody test work?

An antibody test, also known as a serology test, illuminates your previous exposure to Covid-19. During this test, your nurse will conduct a venipuncture or finger stick blood draw.

Concierge MD LA uses venipuncture (blood draw) tests to determine the presence of Covid-19 antibodies with results available within 48 – 72 hours of administering the test.

Your antibody test will scan for evidence of:

  • IgM (Immunoglobulin M) antibodies: These antibodies are your primary defense against any kind of illness and develop early on in an infection.
  • IgG (Immunoglobulin G) antibodies: These antibodies typically develop later in an infection, sometimes after you’ve fought off your illness. These are the most common types of antibodies and are able to remember illnesses you’ve had before, helping provide protection against subsequent infections of the same disease.

Do Antibody Tests Work?

The accuracy of Covid-19 antibody tests are variable according to their manufacturer. Concierge MD LA uses highly accurate tests in our at-home appointments to ensure the highest quality of care.

What is the difference between an antibody test & a Covid-19 test?

An antibody test is different from a Covid-19 test. An antibody test is a blood test that looks for signs of a prior infection.

A Covid-19 test looks for an active presence of SARS-CoV-2 – the current pandemic strain – in your body. This test itself is a nasal swab that must be shipped to a lab for analysis. Covid-19 tests may take 48 – 72 hours for results.

**Should I get both an Antibody Test & Covid-19 test done at the same time?
Some people decide to get both a Covid-19 and antibody test done at once. The combination of tests illuminate both current and history of infection.

Can An Antibody Determine If I Have An Active Infection?

It takes time for antibodies to build-up in the system. This can sometimes happen only after you have recovered from an infection. Therefore, it’s possible for this test to miss an infection if the virus is still in incubation or if your body has not yet manufactured antibodies. However, if your body has started to produce antibodies at the time of your test, it is possible for your antibody test to reveal an active infection.

That said, Covid-19 antibody tests are not designed to look for an active infection. As discussed earlier, this test identifies specific antibodies that your body has made to fight off Covid-19. If you suspect you may have Covid-19, you should seek a Covid-19 test, not an antibody test, for accurate results.

What kind of results can a Covid-19 antibody test show?

There are four possible outcomes of a Covid-19 antibody test:

  • Both IgM and IgG are positive: Your body has an active Covid-19 infection and has begun a defense against it.
  • Both IgM and IgG are negative: You have either never had a Covid-19 infection or the virus is still incubating.
  • IgM is positive, but IgG is negative: You have an active, early phase Covid-19 infection.
  • IgG is positive, but IgM is negative: You have likely recovered from a Covid-19 infection regardless of symptoms or a lack thereof.

What Is The Meaning Of Test Sensitivity And Specificity?

All medical tests have a threshold above which a person is considered to have a particular illness or disease. This threshold needs to be placed high enough to properly classify people with a disease, but not so low that healthy individuals are not included among the diseased population.

  • Test sensitivity is the proportion of diseased individuals correctly identified by the test.
  • Test specificity is the proportion of non-diseased individuals who are correctly identified by the test.

Tests can provide incorrect results according to their specificity or sensitivity. Tests with low sensitivity or low specificity have a higher chance to give incorrect results. On the other hand, a test with high sensitivity is less likely to provide a false negative, while a test with high specificity is less likely to give a false positive.

What are false positive and false negative results?

Although tests are built to be as accurate as is feasible, results can sometimes be wrong. This can result in false positives and false negatives. What do these terms mean?

  • False positive: The tested individual is not actually sick, but tests positive regardless. False positives can also happen if a person is exposed to a coronavirus strain other than SARS-CoV-2, which is the current pandemic strain.
  • False negative: The individual is actually sick despite testing negative.

Getting the correct result is important for a variety of reasons. False positives can lead to additional testing, treatment, expense, and concern for you and your family. False negatives, on the other hand, can lead to a potential spread and worsening of the illness, as you may not seek medical assistance if you believe that you are not sick.

Tests with high specificity and sensitivity can reduce your chances of receiving a false test result. Concierge MD LA uses a high specificity and sensitivity tests for results that are as accurate as possible.

Why Would You Need Antibody Testing?

If antibody testing detects Covid-19 after the illness has already run its course, then you may be curious as to why you should get an antibody test.

Antibody tests are useful because…

  • You can assist health officials gather more information to develop a better picture of the extent and spread of Covid-19 by region, which in turn helps them write improved public health recommendations.
  • You can help health officials understand how the immune system develops after a Covid-19 infection and if previously infected individuals have immunity, further contributing to the public understanding of this novel coronavirus strain.
  • You can identify if you are an asymptomatic carrier and take steps to shield your friends and family to stop them from getting ill.
  • You can know if you’ve had Covid-19 in order to return to work safely.
  • You might become eligible to donate convalescent plasma to assist individuals who are ill with Covid-19 recover from their infection.

Who should have an antibody test?

If you think you are currently ill with Covid-19, you should not get an antibody test. Instead, you should get a Covid-19 test to look for an active viral infection.

You should get an antibody test if:

  • You have been sick with the virus and recovered
  • You want to know if you previously had the infection (with or without symptoms)

How Can You Get An Antibody Test?

Antibody tests can be facilitated by healthcare providers, some laboratories, and some universities. Every state has a different system in place for their RT-PCR, antigen, and Covid-19 antibody testing, so see your state’s guidance to find the closest testing center.

If you are concerned about the public exposure involved in going to a clinic to find out if you previously had Covid-19, Concierge MD LA offers in-home antibody tests for convenient, fast results and peace of mind.



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Concierge MD LA offers coverage throughout the greater Los Angeles area.