Covid-19 Antibody Testing
- 1 What Is The Covid Antibody Test?
- 2 Antibodies
- 3 In-Office Testing
- 4 At Home Testing
- 5 Results Duration
- 6 Antigens Tested
What Is The Covid Antibody Test?
There are two main types of test that exist today related to evaluating if one was (or is) exposed to the COVID-19 virus. One tests for active infection. This generally involves a nasal swab to check for RNA of the virus through a process called PCR. If the test is positive, there is a very high likelihood that one has active infection, although false positives can exist in cases where RNA remnants of the virus are present within the body but he virus is no longer pathogenic. This test is currently not being offered at our office. In fact, if one has any symptoms of infection (fever, dry cough, feeling tired, loss of smell) then they should immediately contact their primary care physician or go to the nearest emergency room if breathing becomes difficult. Our office screens everyone who enters by taking temperature and ensures that health and safety remain our number one priority. For more information on our in-office protocol click here.
The test being offered at our office checks for antibodies to the virus. It does not check for the presence of the virus itself or for active infection. Antibodies are generated by the body in response to an infection and may confer immunity. It may also tell us how long you have been exposed to the virus and what stage of the immune response you are in. The test requires a blood sample to be drawn in the office or at home. The test checks for 4 different antigens specific to COVID-19.
Because the serological antibody test checks for exposure and not active infection, it us possible that one could be actively infected with COVID-19 and still have a negative result if the body has not yet generated a sufficient amount of antibodies during its immune response to be detected. Antibodies are usually generated within a week of exposure but in some people it could take even longer.
Antibodies are also known as immunoglobulin. These are Y shaped proteins that are made mainly by plasma cells to help neutralize viruses and bacteria. Antibodies recognize antigens and attach to them, and, in essence “tag” the microbe (virus or bacteria) for destruction by a white blood cell or macrophage.
There are 3 different antibodies tested: IgG, IgM, and IgA. Testing three antibodies against 4 different and specific antigens against COVID-19 makes this test highly specific. These 3 different antibodies are made throughout different courses of the disease.
IgM is the earliest antibody created, made within the first 3-5 days from time of infection. Production of IgM slows down around day 10-17; serum levels of IgM are markedly diminished after 2 weeks. IgA is made later, and IgG s made last, starting production around day 7. IgG is regarded as the long-term immunity antibody. The presence of serum IgG is generally regarded as long-term immunity to the virus.
Anyone without symptoms (i.e. no fever, cough or sneezing) who can tolerate a venous stick in the arm. Anyone with respiratory symptoms or a fever will not be allowed to be seen or tested.
Every patient is screened for fever before being seen by Dr. Neavin. If a fever or any symptoms are present, patients will be asked to follow up with their primary care physician for further work-up and the test will not be completed.
The test involves a blood draw. One does not need to fast prior to the test. One should drink plenty of fluids to make veins more visible and accessible to a blood draw. The sample will be sent to the lab and results are often back within 3-4 days.
At Home Testing
Depending on location, one may be eligible for at home testing. A phlebotomist can draw blood at your home. Any heath care provider visiting a home will be wearing a mask, eye shield, and any other necessary PPE. The visit generally lasts no more than twenty minutes. A consent will need to be singed for the blood draw and acknowledgement of the implications of a positive or negative result. All health conditions and medications must be shared with Dr. Neavin. At the discretion of the office and availability, home testing may not be able to be performed. The office may recommend an in-office test. Results are available generally within 4-5 business days. Results can be emailed or the office may call. For more information about home COVID-19 antibody testing call the office at 310-858-8811 or text 323-975-1287.
HOW IS THE OFFICE KEEPING THINGS SAFE FOR PATIENTS?
Artisan of Beauty has implemented strict safety protocols, guided by the LA County Department of Health’s guidelines. For one, anyone entering the office is kindly asked to leave if they have any respiratory illness symptoms or a fever. Only patients who exhibit no signs or symptoms will be permitted to be seen. The office reinforces the Beverly Hills mandate that face coverings are required, and social distancing measures are implemented. All surfaces are cleaned with medical grade cleaning supplies after each visit. If anyone enters the office without a face covering, one will be provided to them. Staff wears KN95 or N95 masks and the necessary personal protective equipment to ensure safety. For more on in-office COVID-19 protocols click here.
WHAT ARE THE BENEFITS AND DRAWBACKS OF GETTING TESTED?
Antibody testing for COVID-19 is exceptionally specific and sensitive for COVID-19 exposure. Exposure of 4 separate antigens (parts of the virus that illicit an immune response) will help determine if you at some point have been exposed to COVID-19. While it does not tell you if you have an active infection, it does does you that the virus has entered your body and your body developed a reaction against it and defeated it. In our opinion, the knowledge of prior exposure with evidence of an immune response will make one feel more comfortable returning to work or social activities since the evidence of a successful immune response may confer immunity against subsequent exposure.
However, it is important to note that this is a novel virus. And it is not clear to what extent immunity from subsequent exposures exists. Leading experts believe that a positive antibody tests means that your body will be able to fight a subsequent exposure more easily; and it very well may make one immune to COVID-19 infection for months to years of lifetime. There currently isn’t enough knowledge to determine the exact extent of the immunity.
A drawback to the testing is that no test is one hundred percent accurate. False positives and false negatives exist in any test. A false negative means that the person was exposed but the test did not identify any antibodies. More troublesome may be a false positive. A false positive occurs when the patient was not exposed but the test results show that antibodies were found. A false positive may lead one to believe that they had the virus and are likely immune to a degree, when in fact they are not. Thankfully, false results are very, very infrequent (see section on test accuracy).
False negative tests may also be the results of a comprised immune response. Some medications negatively impact immune responses, such as steroids or cancer medications.
The processing time for the lab is approximately 4-5 business days. As soon as our office receives the lab results, we will either email them to you or call you, along with a guide to interpret the results.
The lab tests for four different antigens: Spike 1 (S1) protein, Spike 2 (S2) protein, Receptor Binding domain (RBD), and Nucleoprotein using qualitative chemiluminescence based antibody detection.
Testing four antigens makes the test more sensitive and specific. Sensitivity and specificity relate to accuracy of results. Sensitivity relates to the test’s ability correctly identify those with COVID-19 (true positive rate). Specificity relates to the ability of the test to correctly identify those who don’t have the disease (true negative rate).
Applying this to the COVID-19 antibody test, testing for 4 different antibodies to 4 different antigens that are highly sensitive and specific to COVID19 makes it very unlikely that a positive test result is the result of COVID-19 exposure; and no other virus strain.
A validation study completed by our partner laboratory done on 340 patients vs. the nasal swab as a control, showed a sensitivity of 97.14% and specificity of 98.36%. This data was submitted to the FDA. This particular test was made with specific antigens from COVID-19 and was tested against the flue and other common cold strains; however, it was not tested against other coronavirus strains. For more information on our partner lab, please visit here. https://www.vibrant-wellness.com/
While you could potentially see cross reactivity, which is why the FDA mandated disclosure is present on all reports, it is very unlikely: Positive results may be due to past or current infection with non-SARS-CoV2 (COVID-19) strains, but the chances are low enough to make this test result very accurate and reliable. Nonetheless, the CDC recommends one continue to practice social distancing out of an abundance of caution until we learn more about the novel virus.
Take Home Points
Negative results do not rule out active COVID-19 infection, particularly for patients who have been in contact with known infected persons or in areas with high prevalence of active infection. To test for the virus itself, a nasal swab testing for viral RNA is in order. It is also important to keep in mind that a positive antibody test does not mean someone actively has the disease, although theoretically they could still have active infection. To rule out active infection, again, a nasal swab looking for RNA of the virus is the proper test — this test is not offered at our office. False positive antibody results rarely occur due to the fact that 4 different antigens specific to COVID-19 are tested. But the chances are not zero. To be more certain about the diagnosis as it relates to any test, it is important to consider clinical findings, patient history, and even rely on alternative testing.
If I Am Positive For Antibodies, Then What?
It is important to note that this is a novel virus. So while we can apply what we know about virology to COVID-19, nobody knows for certainty that immunity develops in the same fashion as it does for other viruses. The data is just not available yet. To that end, everyone should follow CDC guidelines on isolation procedures which currently say that you should isolate for 14 days and be asymptomatic (no fever for three days and seven days since first symptoms) before coming out of isolation.
If you have IgM only, this may mean that you were recently exposed or may have active infection even if you have not symptoms. One should isolate for 7-14 days to be safe.
If you have IgG, this likely means you had and cleared the infection. However, out of an abundance of caution, one should isolate for 3 days and come out of isolation no less than 3 days if one has no respiratory symptoms or fever.
If My Test Is Negative, Then What?
A negative test implies that one has not made antibodies to the virus. This could mean that one wasn’t yet exposed to the virus, that one was exposed but didn’t develop antibodies (as may be the case with men and women on immunosuppressive agents or certain steroids, or one was very recently exposed but has yet to develop antibodies. One could get re-tested in a week or two if they strongly suspect prior exposure. Or, one could get a nasal swab to look for viral RNA to COVID-19 which would indicate active infection or very recent infection.
If one has no antibodies to the virus, one is still susceptible to COVID-19 infection. Thus, one should follow all local orders to shelter in place, practice social distancing, wear a mask when one leaves the home, and continue rigorous sanitation and hand washing.
We know how important it is for people to know if they have been exposed the COVID-19. Thus, we’ve priced the tests as reasonable as possible. The office pays for shipping and the sample as well as all laboratory testing costs. In office test including blood draw and lab results cost $275. Home testing which includes a blood draw by a phlebotomist and lab results cost $390.
Has The Fda Approved This Test?
Physicians and health care providers around the country are providing this antibody test and others in partnerships with labs that are following the FDA Emergency Use Authorization guidelines. And although our partner lab is listed on the FDA website as having submitted their data under section IV.D. of their guidelines, this particular antibody test is not FDA approved or cleared for COVID-19. And it is important to note that this is not diagnostic for COVID-19 infection; the test determines with very high accuracy whether or not you were expose to, or previously infected from COVID-19.
The FDA has stated that developers of certain serological tests may market and use their tests once appropriate evaluations have been performed to determine that their tests are accurate and reliable — which includes allowing manufactures of serological testing for COVID-19 to market their tests without prior FDA review as long as conditions outlined in the FDA guidance document are followed. See below:
Are My Test Results Private?
Our office protects the privacy of patient information. Our lab partner is subject to reporting requirements of the CDC, FDA, and local and state authorities. However, there is presently no mandate to share your results with any governing body. But the climate around COVID-19 testing is dynamic. There is no guarantee that down the line a governing body such as the CDC won’t ask for COVID-19 antibody test results which may supersede all patient privacy rights.