Earlier this week we shared with you some background on blood tests to detect COVID-19 antibodies. Here is some additional information about antibody testing. As always, the following does not substitute for medical advice and is for informational purposes only.
COVID-19 IgG Antibody Testing Differs From COVID-19 Diagnostic Testing In Several Important Ways
Both diagnostic and IgG antibody tests require a physician order when performed through a lab, and cost-sharing for both is waived by the Families First Coronavirus Response Act. Here’s where the two tests differ:
COVID-19 Diagnostic Testing
COVID-19 IgG Antibody Testing
Purpose of Test
|To confirm a current, active infection
|To identify those who had COVID-19 in the past. Many people have mild or no symptoms, and may not have been diagnosed.
|Respiratory secretions from the back of the nasal cavity
How the sample is collected
Type of test
|Molecular test: looks for COVID-19’s viral genetic material
|Serological test: examines the blood serum for IgG antibody proteins which develop in the body a few weeks after an infection starts. IgG antibodies help fight off an infection and stay in the body for a long time after recovery.
Who the test is intended for
|You believe you have COVID-19 currently or have been exposed to it recently
|You are unsure if you had COVID-19 in the past
Who should not be tested
|You should review your COVID-19 symptoms and exposure with a doctor to see if testing is recommended
|Don’t take this test if you want to diagnose COVID-19, or you currently have symptoms of COVID-19, or you think your COVID-19 infection or exposure started within the past two weeks (the IgG antibodies take time to appear so they may not show up on the test if done too soon)
When to take the test
|You are experiencing symptoms of COVID-19 or your doctor or a health official recommends it based on your exposure to COVID-19
|Wait at least two weeks since you were last infected or exposed to COVID-19 to take the test. Required wait period may vary by lab.
What the results mean
|A positive diagnostic test result indicates you have a current COVID-19 infection
|A positive IgG antibody test result means you have antibodies that likely resulted from COVID-19. An antibody test given too early could come back negative even if you had the virus because of the time it takes for the IgG antibodies to appear.
The antibody test does not tell you if you have an active infection. So, regardless of the result, you will still need a diagnostic test to confirm an active infection. Please note, the testing labs may have different testing requirements than those listed above.
Ways Members Can Access Antibody Testing
There are several antibody testing options currently available. A prescription is necessary for the test so if you want to get tested for antibodies you should contact your doctor for a test script.
The most cost-effective locations for testing will be through free-standing labs rather than through hospital labs. A primary care physician (PCP) can write a prescription for you to visit a lab’s patient service center (such as a BioReference Laboratories, Labcorp, and Quest Diagnostics patient service center) for the blood draw. Some PCPs may do the blood draw at their office and send the sample to a lab for analysis; you should request that it be sent to a free-standing, MagnaCare-participating lab rather than a hospital lab which will be much higher in cost.
If you do not have a PCP, you can contact a PCP in the MagnaCare network, a telemedicine vendor you have in your plan, or a self-pay telemedicine vendor like those listed here. Keep in mind that antibody tests ordered or drawn at urgent care centers, hospital-affiliated providers or hospital-affiliated labs will cost the plan more than those ordered by a PCP and sent to a free-standing participating lab.
Otherwise, you can choose to self-pay and schedule an antibody test directly through LabCorp or Quest Diagnostics. You would be responsible for the full cost. These direct-to-consumer options are NOT covered under insurance and cost significantly more than the insurance rates. There are no FDA-authorized antibody home testing kits at the moment.
Reliability of Antibody Testing
According to the CDC, it’s unclear right now if the COVID-19 antibodies provide protection (immunity) against reinfection. Research is underway to confirm if COVID-19 antibodies offer some level of protection as expected.
Many antibody tests are appearing on the market, but they vary in their accuracy. Antibody tests available through BioReference Laboratories, Labcorp and Quest Diagnostics (MagnaCare-participating labs) are said by the labs to meet their standards for specificity and sensitivity. As with any tests, false positives and false negatives are possible.
We hope you find this information helpful as we approach the next phases of our country’s coronavirus response.