COVID 19 Antibody Testing

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Why Do We Want to do a COVID-19 Antibody Test?

Dr. O’Hara: I think you’ll learn a lot. We’ve certainly learned a lot in the last few weeks as we have been investigating COVID-19 Antibody Tests.

We want to understand if someone has some level of immunity (IgG antibodies). We also want to test those who are at higher risk. Those at higher risk are people with obesity, who are immunocompromised, have asthma, elderly individuals, frontline workers, and those who traveled recently. We also want to test anyone who is presumed to have had COVID-19 or has come in contact with somebody with COVID-19 symptoms.

People are most likely not going to get re-infected with COVID-19. However, we don’t 100% know if this is the case. Some people have tested positive and then get another positive when retested. This is likely due to residual viral RNA, not due to a new infection. So if you came in contact with someone with COVID-19 and you have a positive antibody test, there is a certain amount of reassurance, though, again, not 100%. Keep in mind, it is still essential to be smart and cautious because we do not have all the answers about the possibility of reinfection.

Also, testing could be helpful if you’re interested in donating for plasmapheresis to help COVID-19 patients.

Why We Test:

    • To provide some understanding of level of immunity
    • To test those at higher risk:
      • Obesity
      • Immunocompromised
      • Asthma
      • Elderly
      • Frontline workers
      • Those who have had to travel
    • Anyone who has presumed COVID 19 symptoms or came in contact with someone with symptoms
    • People are probably NOT getting re-infected. Anyone who is getting another positive test is due to residual viral RNA
    • We think the presence of antibodies grants probable immunity
    • To donate for plasmapheresis for COVID-19 patients

Why We Might NOT Want to do a COVID-19 Antibody Test?

Getting a positive is not a get out of jail free card. The antibody testing results should not be used as a sole basis to inform whether you have had a COVID-19 infection. There is still a tremendous amount of sensitivity and specificity issues with these tests. There is not enough clarity yet to know if having detectable antibodies does 100% confirm immunity. We think it probably does, but we’re not sure that there could not be a reoccurrence as the virus mutates.

There have not been enough validation studies done yet because all of these tests have been approved under the EUA “Emergency Use Approval” by the FDA. There can be some cross-reactivity with other coronaviruses. It can take up to two weeks for an IgG antibody to become positive. So, if you recently have become infected, you may not be positive. Specifically, we have an infection rate that we think is about 3% for COVID-19. To get a test that is really accurate, you need at least a 99.7% specificity. Most of these tests, as of yet, do not have that. Thus, you will have some false positives, as well as false negatives.

Why We Might Not Test:

    • Because you think this is a “get out of jail free card”
      • Results from antibody testing should not be used as the sole basis to diagnose or exclude SARS-CoV-2 infection or to inform infection status
      • There is not yet clarity that having detectable antibodies confers immunity. Thus, we don’t know if having antibodies prevents recurrence as the virus may mutate
    • Validation studies have not yet been done because of the use of emergency approval by the FDA
    • Cross-reactivity (false positives) with other coronaviruses
      • coronavirus HKU1, NL63, OC43, or 229E.
    • It can take up to 2 weeks to see an IgG antibody response
    • For an antibody test to work in a population with an infection rate of 3% (like COVID -19) we need a test with 99.7% specificity

Which Antibody Tests to Use?

We have vetted over 15 different companies that are offering antibody testing. We have ruled out the pinprick test done by several labs because the ones being offered now have a much higher rate of false-negative and positives. So again, we go back to focusing on the tests’ specificity and sensitivity. They were all designed under the EAU “Emergency Use Approval” so they’re still determining the accuracy of each test.

The NECFH office will continue to provide nasal pharyngeal antigen testing for acute infection, but it is preferred that you go to a local drive-through testing center or go to your pediatrician or your PCP.

  • We have vetted over 15 different companies offering antibody testing
  • We ruled out all testing done by pinprick because false negatives and positives were much higher
  • Antibody tests are developed to prove immunity but because all were designed under emergency use, all are still determining the accuracy of each test.
  • We will continue to also provide nasopharyngeal antigen tests but it is preferable to go to a local drive-in testing center or your pediatrician.

Tests Available at NECH

(Current patients and immediate family)

This chart shows tests that we have vetted and our office recommends currently.

Again, we vetted over 15 different labs. We will be using Quest for those of you who cannot afford either specialty labs; we presume that Quest’s test should be covered by your insurance as it is approved under the EUA but there’s no guarantee. We have the appropriate codes and will do everything we can, but if your insurance doesn’t cover it in retrospect, there will be nothing we can do.

You can try and submit testing through Boston Heart and Diagnostic Solutions tests but since their approval is still pending, we do not have a definite assurance that those tests will be covered.

Specificity vs. Sensitivity

  • Specificity is how many false positives.
  • Sensitivity is how many false negatives.

Quest COVID-19 Antibody Test

We do not like the Quest test because it is not quantitative, and there is no real known on this test’s specificity or sensitivity.

So, if we do this testing on you or your child, we would recommend doing the Quest together with one or two of the other ones. This way, we will get our own internal specificity and sensitivity information out of this.

Boston Heart Diagnostic Solutions and Diagnostic Solutions COVID-19 Antibody Tests

  • Boston Heart is quantitative. Boston Heart is providing the numbers.
  • Boston Heart has a 96% specificity, meaning there is a 4% false positive.
  • Boston Heart has a 95.6% sensitivity, meaning there is about 4- 5% false negative.
  • Diagnostic Solutions, although they say they are quantitative and gives a high, low, or negative effect. So they are not providing the specific numbers to us.
  • Diagnostic Solutions, within their own clinical study, says that their specificity and sensitivity is 100%.

When you’re dealing with a disease that is only 3% prevalence, Boston Heart has a somewhat inaccurate high specificity and sensitivity i.e., a high false-negative and positive rate. But this is the best we can do. The Diagnostic Solution’s numbers are only from their own clinical study. So having said all of that, we like both of these tests best of all the 15 we vetted. Using the Boston Heart test as an example, out of 100 tests, 95.6 will be correct, and 4.4 will be falsely negative when they should have been positive.

If you can afford to do one or both of these two specialty labs, and you as a parent or your child has had COVID-19 symptoms or fit into one of those high-risk criteria of coming in contact with COVID-19 like traveling or had symptoms recently, we ask you to do both tests so we can continue with our internal test review. We want to see if they are equally accurate.

Mount Sinai Testing

If you or a family member have had a positive antigen COVID test, you are eligible for testing with Mount Sinai. It is the only one with full FDA approval. We can get that test for you if eligible.

Getting Tested at NECH

NECH is open by appointment during the week and on Saturdays for active patients of the practice and immediate family members. Please message us through the patient portal. We stagger patients so only one patient at a time is seen and we sanitize in between patients. If your child needs any assistance to get a blood draw, we require an additional caregiver to help. Everyone must wear gloves and a facemask. We will do temperature checks before entry.

Social Distancing Still Recommended Regardless of Results

We want to reiterate that regardless of the results, if your test is positive or negative, we’re still recommending social distancing, wearing masks and gloves when you’re out in public, hand washing, and making good decisions for you and your family. Remember, testing is not a Get Out of Jail Free card.

If you are having anyone come to your home or business, make sure you wear masks and maintain a 6-foot distance while they are there and disinfect after they leave.

Questions & Answers

Will they accept the results of an antibody test prior to going into the hospital for childbirth?  You will have to do the nasal pharyngeal swab as the antibody tests aren’t FDA approved. But knowing what the antibody test results may give you peace of mind prior to going in.

Can we give blood if we have positive antibodies to COVID-19 to someone who has had Lyme disease in the past? Each hospital will have a different set of criteria for whether they would accept it or not. I know that at Yale, they do ask if you have an active Lyme infection.

Are asymptomatic positive people making antibodies? This is the information we’re looking for. We are very hopeful that people who have been asymptomatic but exposed will have antibodies. We are looking to test asymptomatic family members who have been exposed so we can prove this.

How long does it take to get the results? It is about a week to get results from Quest but that might be a little longer as demand increases. For the specialty tests, it takes about 10-days but we can only send those out on specific dates so may extend the time.

Will the antibody tests get more accurate over time? An individual test is not going to become more or less accurate. This is about statistics; how many people out there are actually asymptomatic with COVID-19. If this disease is much more prevalent than we expect because there are so many asymptomatic people, as many as 20% of the population may be positive in some small studies, then that 95-96% accuracy will then be sufficient and considered much more accurate. We truly now need to gather more information before this question can be accurately answered.

When do you think is the earliest most of us could have been exposed to COVID-19 if we were traveling to “hot spots”?  Many ask about whether or not their illness back in January could have been COVID but it is most likely to have been the flu. Many with the flu this year presented with coughing and was bi-phasic but it was still the flu. There were reports about people having COVID in Italy and other areas as early as December. So it is possible, especially if you were in China, NYC, Seattle, or other hot spot and then sick after. We would recommend getting tested.

Should you get antibody testing before entering back into a group environment? Again, antibody testing is unfolding. It might give you some sense of security, especially in our immunocompromised patients. I hope that they’re testing everybody that goes back to school right now. Testing periodically, the nasal pharyngeal testing, should be done regularly as well. We think everybody who is out in the community should get their temperature taken every day. We will be doing this in our office.

If someone tests positive for antibodies, how long do you think one maintains these antibodies?  That’s one of those $64 million questions because this is a novel virus. If we look at similar viruses, you can maintain immunity for a year. It could be life long. There are some viruses where we maintain immunity for as long as 10-years. Please note that many viruses mutate into a slightly different form of the virus. We feel that the prevalence of this virus antibodies will provide some level of immunity. This as well as herd immunity is what is needed over time. But there are still too many unknowns right now.

What is the privacy of these tests? If you have a positive antibody test, the labs should be reporting it to the CDC as required by the FDA for their counts. They will be HIPPA compliant.

What other labs did you look at for antibody testing? We looked at Abbott and Ortho Clinical, which are FDA approved; the specificity and sensitivity of those are not better than the two we use here. The Abbots and Ortho Clinical, as well as others, require certain machinery in your office or CLIA certification, which in our small office we do not. So, we chose tests that are both from labs we trust and have used for years. We trust the clinical acumen of them and the veracity of their numbers. Plus, they’re very similar to the ones that have been approved.

We did look at the Igenix test, but it is not approved for EUA and it is over $300, so we will not use it now.

How do we know which test to do – Antigen or Antibody testing?  This depends on how long you’ve had symptoms or how long it has been since you had any symptoms. If you’re within that 14-day timeframe of having symptoms, you should get a nasal pharyngeal antigen test. If you have had symptoms for longer than 14-days and symptoms have decreased but have not completely cleared up, get the nasal pharyngeal. At the 14-day mark, your body might not have mounted antibodies yet.

If somebody tests positive but hasn’t had symptoms for four weeks, could they still be contagious? Unlikely, because it is past the two-week timeframe. But again this a novel virus and there is some information out there that people have an active infection for longer. If they still have IgM antibodies, they could be contagious.

I do not. But contact tracing in this country has been very poor. In areas like China, where there is better contact tracing, there are not reports of that happening. But there are definitely reports of people who have met in groups in outside settings who stood about 6-feet apart that did contract it.







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