Antibody screening is done through a blood test that checks if you have been previously infected with the virus that causes COVID-19. If you had the coronavirus, your immune system may have produced antibodies to fight the infection. The common antibody test detects IgG antibodies.
Antibody tests are different from the PCR swab test that you may be familiar with. While the antibody test assesses past infection, the PCR swab test assesses current infection with COVID-19. For more information on the differences between these tests and which test is best for you view this link.
When Should You Get an Antibody Test?
Since the antibody test assesses past infection, you should not get a test if you currently have symptoms of COVID-19. According to the CDC, it typically takes at least 1-2 weeks after getting sick for a patient to develop the antibodies for COVID-19. If you were previously sick, tested positive for COVID-19 on a PCR test, or were exposed to someone with COVID-19, you may want to get an antibody test. However, it is important to note that many doctors are still not recommending getting tested because the tests are not highly accurate.
How Accurate Are These Tests?
In order to be approved, antibodies must have a sensitivity of 90% and specificity of 95%. Sensitivity is the ability for a test to detect a true positive result (presence of the antibodies) and specificity is the ability for the test to detect a true negative result (the absence of antibodies).
This all means that even if you test positive, there is still a chance that your results are a false positive. In fact, in areas where there is a low prevalence of COVID-19, the number of false positive tests has been nearly the same as the number of true positives. Before getting an antibody test, research the type of test that you will get and its accuracy. Some of the more accurate tests include those developed by Mount Sinai Hospital and Roche Holding AG.
What do Positive and Negative Results Mean?
As many states have surpassed their peaks and started the process of reopening, it is important to understand your test results and what they mean in terms of social distancing.
If you test positive…
If your test comes back positive, you may have the antibodies for the virus that causes COVID-19
It is currently unknown whether having the antibodies protects an individual from reinfection for two reasons. 1) Physicians are not sure what quantity of antibodies is necessary to confer immunity and 2) Some of the antibody tests measure different types of antibodies associated with COVID-19 - it is unknown whether all types of antibodies provide immunity to COVID-19
For these reasons, even if your antibody test comes back positive, it is important to continue practicing social distancing and following the CDC health regulations for your region
If you test negative…
If your test comes back negative, it is likely that you do not have the antibodies for the virus that causes COVID-19
If you were tested after a decent diagnosis with COVID-19, it is possible that your body did not produce the antibodies yet
Where to get a test
A membership with Mira gives you access to low cost laboratory tests, including the COVID-19 antibody test