There have been approximately 5 million confirmed cases of Covid-19 around the world. I’m one of them.

In March, my partner, a sheriff’s deputy and first responder in New Hampshire, tested positive for the disease. A few weeks later, so did I. Our symptoms varied, and his were more severe than mine. We both feel fortunate to have recovered. But, like millions of others who have done so, we’ve been left with a burning question: Now what?

Are we now immune from future infection? And, if so, for how long?

advertisement

Serology testing — otherwise known as antibody testing — can indicate whether someone is producing an immune response to the virus. And in recent weeks antibody testing has become more widely available in the United States, including a test from Quest Diagnostics, which allows consumers to order it directly online before being directed to a local lab.

So a couple of weeks ago, I took it, eager to finally have some clarity on my own health. What I learned gave me some peace of mind, but also underlined how many questions the science still can’t answer yet. 

advertisement

The process of getting tested was quick and simple. I went online, ordered a test, and made a same-day appointment at a lab. All it took was a small blood draw and by 3 a.m. the next morning my results were waiting in my inbox. (Others have reported getting results has taken much longer.)

Here they are:

spinelli_result

The results were clearly intended to be straightforward enough. But for a layperson such as myself — and I’m sure for others like me — the results were also confusing. Clearly I was producing antibodies, which was a good thing. But to what end? 

I contacted Quest for answers and was put in touch with Andrew Abraham, a physician who works for PWN Health, a national clinician network company that partners with Quest to provide assistance to clients.

Abraham was patient with my questions, and explained that when people get sick with an infection they actually produce two kinds of antibodies, IgM and IgG. The IgM antibodies are the first, fast-acting antibodies that work to fight off a virus, but they don’t stick around. They do, however, stay around long enough for your body to then create IgG antibodies, which stay with you much longer depending on the virus it’s protecting you from. 

When a new pathogen causes illness, the immune system creates memories, so its cells can target and kill the invader if it ever comes back again. Here’s how a person becomes develops immunity. Hyacinth Empinado/STAT

The reality is that, as a result, my body would likely fight off the virus if I encountered it again. But Abraham cautioned that I’m not invincible. At this point, science has no way of telling how long my IgG antibodies will remain with me.

“We want to make sure the consumer understands that there are some limitations around the test and that unfortunately, at this point, we can’t see it as a passport to immunity as was once kind of widely heralded as the panacea to Covid,” PWN’s chief medical officer, Doug Elwood, told me.

At the moment, PWN only validates two tests: the one from Quest, and another from LabCorp. What made them so special? 

Both tests meet the company’s criteria for specificity and sensitivity, crucial terms of understanding antibody testing.

When assessing the test’s accuracy, “sensitivity” refers to the ability of the test to detect antibodies to SARS-CoV-2. A test with a low sensitivity will produce more false negatives, telling people they haven’t been infected with the virus when they have been. “Specificity” refers to a test’s ability to return a negative result when people really haven’t been infected with the virus. A test with a low specificity will return more false positives, telling people they have been infected when they really haven’t.

Quest’s test has a sensitivity rate of over 90% and specificity 99% to 100%. 

That leaves open the possibility that some very small number of people’s results will be false-positives or false negatives. And it means that taking the tests do come with some risks, like virtually any test.

When I asked Quest’s chief medical officer, Jay Wohlgemuth, who the company believes should be getting a serology test, he said the ideal candidates are people who believe they may have been previously exposed to the virus but are no longer sick. “For anyone who is sick, they should be getting a PCR test,” Wohlgemuth said, referring to the nasal swabs that help diagnose active infections.

The population of candidates for the test is likely sizable. Given a monthslong shortage of Covid-19 tests in much of the country, there are countless people who think they may have had the disease — but aren’t sure. And some people may have had PCR tests and come up with false negatives.

My own experience was a mixed bag. I wanted to find comfort in being told that my restlessness over Covid-19 was for naught — and that my partner and I aren’t going to be infected again. I wanted that peace of mind that, even with a mask on, I’m never going to be at risk of infecting others when I’m going to the store or walking my dogs — if I get sick again. 

The reality is that science can’t yet offer me, or any of us, those assurances. 

I’m not an unabashed optimist. I realize there is still so much that we don’t know about Covid-19. But having answers, even fleeting ones, has allayed some of my concerns for now. 

  • I question how long COVID antibodies remain positive over time as well. I am a physician in Oregon. I am a clinician and not a researcher but we performed a voluntary observational study on our Urgent Care staff. The results are available to review on http://www.efmpc.com under the tab “Evergreens response to COVID-19”. There is some community evidence that IgG antibodies do not last very long after recovery from an infection. I am not certain but it suggests that there may be more false negative serologic results with remote infections of SARS-CoV-2.

    John Powell M.D.

    • Dr. Powell,
      Thank you for doing the study and letting us know about it. I have seen a paper, or a preprint, or some kind of news of research, (I am sorry, but as a layman I have not been careful to keep references, I am going to work harder at it) anyway, the conclusion was, patients from the SAR epidemic, at least some patients, had antibody to both SARS and CoV2, and I think they said it was a neutralizing antibody.
      I just realized – I replied to you to let you know about what I thought was lasting immunity, but now it occurs to me, the antibody may have been from a sample taken at the time of that outbreak, and frozen ever since, so I do not know if it persists in the body or not.
      Now that I think of it, maybe the main point of the report was that if there was an antibody which worked against both SARS and CoV2, then they share some part which has been conserved after a lot of mutation.

      Sorry for rambling but if that antibody persisted it would be very relevant to your concern, right?

    • Sorry for my previous rambling comment, it did not really relate to yours, but anyway, the antibody is S309 and is now a target for both vaccines and treatments according to the reports.
      It occurs to me, even if S309 antibodies did not persist in the body naturally, if they work against this virus and others, we could maybe give everyone a shot every year or couple of years and avoid the worst of this new disease.

  • I tested positive for antibodies at higher levels, I never felt sick, so reading this article helps me understand a little more, I’m a painter for NYCHA.

  • Is there nothing to worry about antibodies test? Does the result show that he/she is immune to the virus? If it is positive, he/she will be recovered soon?

  • is it correct that immunocompromised people who have had Covid would more likely not make antibodies so the test would be negative.

  • Steve: The IgG antibody that Alexander’s test revealed _is_ a neutralizing antibody. He got better, right?
    Your other questions are still mostly open: how will antibody levels hold up over time; what happens if virus or spike protein mutates; etc. The vaccine-induced antibody questions are the whole reason for clinical trials.

  • The best Covid-19 antibodies test to date is made by Quotient : 100% sensitivity, and 99.4% specificity (only 0.6% false negavites). This is almost perfect, and much, much better than Quest’s OR Abbott Labs tests. Quotient’s tests are used all through Europe. This is the winner among current tests …… (ticker QTNT).

    • Yes – Steve, if the US is willing to work with the Swiss company Quotient, just like the UK and several other countries already do – then the better tests from elsewhere in the world can be used by US people. But you’d have to convince Trump that it really is a good move.

  • The problem with widespread COVID-19 antibody screening is the prevalence of people with COVID-19 antibodies is likely quite low, so even if 90% sensitivity and 99% specificity sounds acceptable, the positive predictive value is going to be very low and lead to a lot of false positives. So many people will get tested, think they have IgG antibodies and are protected, when in reality a majority won’t be. That’s a dangerous scenario as the country reopens and could easily lead to their being a worse second wave. In reality, people should be getting the antibody test 2 or 3 times before they can be confident in the result.

    • I had an extreme inflammatory reaction back in the beginning of March after having stroke-like symptoms. I had only a moderate fever at the end of February.

      I went to the ER for the stroke symptoms, but as a younger female, I wasn’t taken seriously, so I didn’t go back during the inflammatory reaction. Also because I thought it would pass, and I only go to ER when there is a possibility of preventing permanent disability. Well, I had symptoms of a heart attack after that, so returned to the ER. They again didn’t take me seriously.

      I got the COVID antibody test finally in May-it was negative. Problem is I’m struggling with lingering cognitive and neurological problems and severe fatigue. I’m at a loss for what I’m supposed to do to get any help. People should understand that not having a diagnosis has dire consequences, especially for females. And how does one get FMLA with no diagnosis? It’s hard enough when you can barely get through the day, but now am also fearful of the consequences of having no help because there is no acknowledgement of the problem.

      This is really concerning. Is there any help for people in this situation?

  • If the author or someone else can answer me – which antibodies are they looking for? There are some antibodies identified as “neutralizing” in some papers or preprints, and, I do not know if those findings are confirmed or not, but seems like having those, not just any antibody, is crucial.

    There are preprints saying some antibodies generated in response to vaccine candidates, using Spike protein, actually will shield the virus from neutralizing antibodies- so it is bad to have them – and finally, of course, the antibodies which enhance disease, if they exist for Cov2, which is not clear to me.

    This article needs to tell me if the test I could get will actually identify NEUTRALIZING antibodies, not just past infection or exposure.

    • A recent preprint – or maybe an actual peer reviewed paper – anyway, a report of research indicated someone had identified an antibody to SARS, Cov1 from 15 years ago, from a recovered patient, which neutralized that virus, AND Cov2 both.
      This tends to indicate that part of the virus is conserved, because the old virus is really not all that similar to the current one – but that part of both seems to be the same – so it is probably the same because any mutations got selected out – and it could be a really good target for a vaccine – maybe to even more viruses we do not even know about yet if you think about it .

      Lots of good news – just do not get infected for a year or two and you will probably be fine.

    • All the antibody tests available detect antibodies that bind to virus capsid proteins. Tests for neutralizing antibodies are very cumbersome, take a long time, and are not appropriate for rapid tests. Unfortunately, they require live virus, so they are a lot more dangerous to run in this case. Since this virus is so new, there are not versions available that have the outside capsid, without the nucleic acid code inside that causes the illness. Until these kinds of tools can be developed, the neutralizing antibody test can only be run in specialized research labs with the proper containment for high level pathogens.

    • Amy, thank you for the reply – I think I understand that, to determine if antibody X is actually neutralizing requires a lot of work in a research lab handling live virus to see if you can infect an animal even though that antibody is present.
      1. Ensure Antibody X is present in live animal.
      2. Inject animal with virus.
      3. See if animal get’s sick.

      What I meant was, having identified only antibodies presumed to confer immunity, if the testing was only testing for those proven antibodies?

      Am I off base with this question? For example, I can imagine, after a vaccine is developed, if it is not perfect, before putting an uninfected doctor in the Covid ward, she will be given a vaccine, perhaps using only one part of virus as antigen, then tested for antibody to that part alone.

  • There is so much information that changes daily about this virus. I am sorry that you and your partner had to experience it first hand . Thankyou for this well written article. It has provided clarification about the antibody tests And what they mean. Stay well

  • Thanks for sharing your antibody testing process with us, Alexander.
    When you requested the test from Quest, did they require an Rx from your physician in order to give it to you? Or might we bypass that step?

Comments are closed.

A roundup of STAT’s top stories of the day in science and medicine

Privacy Policy