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Study Finds Nearly Everyone Who Recovers From COVID-19 Makes Coronavirus Antibodies

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Credit: NIH

There’s been a lot of excitement about the potential of antibody-based blood tests, also known as serology tests, to help contain the coronavirus disease 2019 (COVID-19) pandemic. There’s also an awareness that more research is needed to determine when—or even if—people infected with SARS-CoV-2, the novel coronavirus that causes COVID-19, produce antibodies that may protect them from re-infection.

A recent study in Nature Medicine brings much-needed clarity, along with renewed enthusiasm, to efforts to develop and implement widescale antibody testing for SARS-CoV-2 [1]. Antibodies are blood proteins produced by the immune system to fight foreign invaders like viruses, and may help to ward off future attacks by those same invaders.

In their study of blood drawn from 285 people hospitalized with severe COVID-19, researchers in China, led by Ai-Long Huang, Chongqing Medical University, found that all had developed SARS-CoV-2 specific antibodies within two to three weeks of their first symptoms. Although more follow-up work is needed to determine just how protective these antibodies are and for how long, these findings suggest that the immune systems of people who survive COVID-19 have been be primed to recognize SARS-CoV-2 and possibly thwart a second infection.

Specifically, the researchers determined that nearly all of the 285 patients studied produced a type of antibody called IgM, which is the first antibody that the body makes when fighting an infection. Though only about 40 percent produced IgM in the first week after onset of COVID-19, that number increased steadily to almost 95 percent two weeks later. All of these patients also produced a type of antibody called IgG. While IgG often appears a little later after acute infection, it has the potential to confer sustained immunity.

To confirm their results, the researchers turned to another group of 69 people diagnosed with COVID-19. The researchers collected blood samples from each person upon admission to the hospital and every three days thereafter until discharge. The team found that, with the exception of one woman and her daughter, the patients produced specific antibodies against SARS-CoV-2 within 20 days of their first symptoms of COVID-19.

Meanwhile, innovative efforts are being made on the federal level to advance COVID-19 testing. The NIH just launched the Rapid Acceleration of Diagnostics (RADx) Initiative to support a variety of research activities aimed at improving detection of the virus. As I recently highlighted on this blog, one key component of RADx is a “shark tank”-like competition to encourage science and engineering’s most inventive minds to develop rapid, easy-to-use technologies to test for the presence of SARS-CoV-2.

On the serology testing side, the NIH’s National Cancer Institute has been checking out kits that are designed to detect antibodies to SARS-CoV-2 and have found mixed results. In response, the Food and Drug Administration just issued its updated policy on antibody tests for COVID-19. This guidance sets forth precise standards for laboratories and commercial manufacturers that will help to speed the availability of high-quality antibody tests, which in turn will expand the capacity for rapid and widespread testing in the United States.

Finally, it’s important to keep in mind that there are two different types of SARS-CoV-2 tests. Those that test for the presence of viral nucleic acid or protein are used to identify people who are acutely infected and should be immediately quarantined. Tests for IgM and/or IgG antibodies to the virus, if well-validated, indicate a person has previously been infected with COVID-19 and is now potentially immune. Two very different types of tests—two very different meanings.

There’s still a way to go with both virus and antibody testing for COVID-19. But as this study and others begin to piece together the complex puzzle of antibody-mediated immunity, it will be possible to learn more about the human body’s response to SARS-CoV-2 and home in on our goal of achieving safe, effective, and sustained protection against this devastating disease.

Reference:

[1] Antibody responses to SARS-CoV-2 in patients with COVID-19. Long QX, Huang AI, et al. Nat Med. 2020 Apr 29. [Epub ahead of print]

Links:

Coronaviruses (NIH)

NIH Begins Study to Quantify Undetected Cases of Coronavirus Infection,” NIH News Release, April 10, 2020.

NIH mobilizes national innovation initiative for COVID-19 diagnostics,” NIH News Release, April 29, 2020.

Policy for Coronavirus Disease-2019 Tests During the Public Health Emergency (Revised), May 2020 (Food and Drug Administration)

78 Comments

  • sw says:

    Telemedicine is making a very positive contribution to healthcare during the pandemic and is being used in a variety of ways. Thanks for sharing this informative article.

  • Ms Susan Harding says:

    I have not been confirmed as having coronavirus virus. I had every symptom of the virus in February 2020 a few days after my return to Chatham Kent after spending time with my family who live in Windsor Berkshire-traveling via London. At the time the reports of the virus were new so I thought was just a general winter virus. As my possible infection was 3 months ago I thought I may be of value with tests on anti bodies

    • Kimberly says:

      Same here trip from Florida first week in February I get sick they said I had double pneumonia I was hospitalized for six days but there was very little conversation about corona at the time I did go yesterday for my physical and my doctor suggested let’s see if you had it by checking for antibodies so we will see the results today.

      • Billy says:

        what were the results?

      • Nick says:

        Same here! Both of my parents were very sick in February, especially my mom. I didn’t feel it either but my parents had just about every symptom except for a fever, but because they didn’t have a fever, we couldn’t get tested because there weren’t enough tests available. I would love to know if we had it or not.

      • Jerald F J says:

        January I was fighting a respiratory illness, by end of month was very sick, negative chest exray but very tired, slept alot, night sweats, no appetite, weird dreams, chest congestion. After 4 days ok to return to work but still very tired.
        May 10th had antibody test at Quest Diagnostic…Negative. Perhaps tested for wrong antibodies can anyone explain?

        • carlybm says:

          It’s really strange and frustrating! My husband tested positive for corona mid April and had antibody testing done at LabCorp on Thursday. Friday his results came back as being negative for antibodies… I read this about potential explanations for a negative antibody test after having corona…
          “But it is possible that people developed antibodies that recognized a different viral protein than the one used in the test, producing a false negative test result.”

          I spoke to several doctors in our family and they all agreed that physiologically, it doesn’t make sense that your body would not develop antibodies after fighting off a virus, regardless of what kind of virus it is. I would think this would especially be true with corona because it is brand new and completely foreign to the body.

          • Scott says:

            I’m in a similar situation… My family (myself, wife and daughter) was sick back in March, first it was my daughter who was already symptomatic after having to return home from abroad. My wife and I became ill about a week later after being exposed with her. We quarantined and isolated from the public but did not isolate our daughter in our house (its too difficult as we do not have the amenities). My wife and daughter both loss taste and smell and I did not. We all had a varying range of the known and lesser known COVID-19 symptoms, I was sick for about 2.5 weeks, my wife about 10 days and my daughter about 2 to 3 weeks. We were all tested for antibodies last week (mid May), my wife and daughter tested positive for IgG antibodies but I tested negative! I have not read about the possibility of a false negative due to a different viral protein. I have read from two different sources that actually 1 in 3 people who are exposed to COVID-19 and become ill do not produce antibodies. So I’m left somewhat puzzled… and because this is a new virus there are no clear answers…

          • carlybm says:

            Where did you go to take the antibody test? We went to LabCorp and they use an Abbott test. . . I know that the antibody test is obviously different than the rapid test, but it makes you wonder about the validity of their tests completely.

            Also, the conflicting information is so confusing! I’ve read several articles that say everyone should develop antibodies. One body of research even said anyone who has had covid should have “robust immunity.” Obviously one study isn’t enough to go off of and I feel like anyone who has had covid should just act like they haven’t and continue taking precautions. But it would be nice to have some accurate tests and conclusive information!!

          • Denise Kl. says:

            Agreed! My daughter’s coworker went to New York in late March to work in the hospitals with Covid patients and had a severe case of Covid19. She tested positive with a swab test. She just returned to Michigan and had an antibody blood test and was negative. I really don’t think there is enough information to say these tests are accurate.

          • Scott says:

            My daughter and myself tests were done at a local urgent care, it was by blood draw and not the rapid test and bloodwork was sent out of town for testing waited about 5 days for results, I’m assuming its the Abbott test. My wife had here test done at Quest by blood draw and obtained results in about 24 hours. The amount of IgG antibodies noted for myself was not even marginal, my daughter and wife both had IgG levels of greater than 1.0. I think there might be two probable explanations for me:

            1. It was a false negative test, but would the result be such that it would detect no IgG???

            2. I may have what is called “cell mediated immunity”, from what I understand this is when T fighter cells in the immune system isolate and kill the virus before the immune system can generate IgG antibodies. I also go to a chiropractor on a regular basis (1-2 times a week) and from what I understand there may be some correlation with chiropractic adjustments stimulating the nervous system to boost the immune systems T fighter count. Also, there is some documented research that sounds like its ongoing to determine if T fighter cells have “memory” to destroy virus cells to prevent re-infection (kind of another form of antibodies?), but I’m not taking any risks and still follow all guidelines.

            Since I was antibody tested in May and was sick in March and recovered in early April, about 5 weeks have passed since I recovered and about 8 weeks since I first became ill. I also was swab tested at the ER (about 6 days into being symptomatic) in March. Swab test was negative for COVID, my wife and daughter were not swab tested. I feel it is highly unlikely that I did not contract the virus after definitely being exposed to the virus as the rest of my family was sick (both having one of the most significant symptoms: loss of taste and smell), and tested positive for antibodies. Its not even I had a low exposure to the virus. I also was symptomatic: started with diarrea, then GI pains (ER suspected appendicitis based on abdominal CT scan), then body aches & chills and fatigue, then chest discomfort and burning that would come and go for hours on/off this was for about a week to 10 days, then some chest tightness but mild. After about 12-14 days, symptoms (headaches, fatigue, body aches and chest discomfort) nearly stopped for 1-2 days then would come back for another 2-3 days but they were milder than the first 10-14 day onset. After about 20-21 days it ended.

          • carlybm says:

            Wow, that’s so bizarre! It definitely makes me feel like the issue has to be the accuracy of tests and not whether or not people make antibodies. If people make antibodies for the strains of corona viruses that just cause common colds, there’s no way they wouldn’t make antibodies for a much more potent corona virus.

          • Scott says:

            There’s two main issues here, accuracy of testing and what is truly unknown, speculative and/or assumed information. I have to think its possible that there is a certain number of people that are not producing antibodies, there was a report out of China that they found 30% of recovered COVID infected people tested negative for antibodies. I don’t think the inaccuracy of the testing could be at least 30%, but who knows? maybe, because I read the swab test at one point had only an accuracy of 70%, thats pitiful! Another medical related organization reports 1 of 3 people who recover are testing negative for antibodies. Also, “cell mediated immunity” is not just a some new explanation for COVID w/o antibodies, it is dependent upon an individual’s immune system response to most viruses and bacteria. You mentioned about viral protein in relation to the virus and detection in the antibody test, not something I searched about but is intriguing also. Unfortunately, for all of us there are just too many unknowns and factors involved.

        • Nick says:

          Yep! We were certain we had it as well back in February but our antibody tests came back negative. In both cases, probably just a more severe case of the flu that just happened to be at a time where a pandemic is occurring.

        • Marian says:

          If you asked the antibody test for the covid19, it’s very unlikely they tested you for something else. The most probable hypothesis is that it was a different respiratory virus, especially if you say you had chest congestion, but negative chest x-ray (sars-cov-2 can provoke an interstitial pneumonia, visible with a simple x.ray)

    • Ishtarella I. says:

      I had the covid-19 while traveling in France for 3 weeks in February. I got all the symptoms, including loss of smell and covid fingers.

      My husband (who got a milder version) and I could not get tested in February. We went for an antibodies test 2 days ago and just got our results : NEGATIVE.

      The test we took (Quest Diagnostics) is supposed to be reliable. I can only suppose that we are no longer producing enough antibodies for the test to detect them.

      We might try again later but we’re still sure that what we had was neither a common cold nor the flu. That deep and dry cough is like nothing else.

  • Teresa Ramos (MD PhD Immunologist) says:

    A number of studies have now shown that ab are produced after infection with Covid 19, what now one look at is whether these Ab are neutralizing! Having Ab does not mean protection. They could even be enhancing! It seams to me that it is important to alert people for this fact for knowing that one has Abs might give a false sense of security.

    • Lauren S says:

      I tested positive for COVID 19 with mild symptoms on 4/2 but on 5/15 tested negative for antibodies. how is this possible?

      • Brits says:

        As far as I can tell, no test is a “gold” standard. Only by taking enough samples tests to create a statistically valid result, can we reasonably discern which approaches are effective. Best wishes to you that you remain healthy!

      • John says:

        I had the same thing and I had the same thing

  • Sandra Libby says:

    I am a blood donor (O Neg CMV neg) and in 2006 I received a note from Hema Quebec saying I have Anti M in my blood and to be careful of transfusions. I don’t know to what or when I formed this antibody. Would this antibody be good against Covid 19. I presume its IgM..If I were to be tested for the Covid 19 antibody, would there be a way to tell that it isn’t the antibody discovered in 2006? Thanks for any info.

  • Emma says:

    Note that it says “In their study of blood drawn from 285 people HOSPITALIZED with SEVERE COVID-19.” There have been reports that those with mild cases of COVID-19 do not produce antibodies, likely because their innate immune system (cell-mediated immunity) wiped out the virus before the adaptive immune system (antibodies) had to kick in. Not much solace for those of us who had “mild” symptoms and were nonetheless extremely ill with fever, nausea, chest pain, and shortness of breath; we’ll never know if we had it, we won’t be able to donate plasma, and we won’t know if we’ll get it again in a short period of time.

    • Kwaaikat says:

      Cell mediated immunity and antibodies are both part of the adaptive and innate immune systems. When acquired after an infection, both protect against future infections.

      Both can be a response to serious or mild infections. New approved anti body tests have near 100% detection rate of past infections (some of which were identified for testing through contact tracing rather than symptoms), which suggests that as with most viruses, cell mediated immunity is rarer.

      It is of course possible for some, which means our immunity estimates derived from anti body testing will be conservative.

      Developing symptoms but fighting it off with innate immunity is a paradox. You can only recover from an illness without an anti infectious agent medication if you develop increased immunity during the course of the infection. If you have sufficient innate immunity to recover, you cannot get infected.

      Individuals for whom a mild infection does not confer relatively lasting immunity, will also not respond to vaccinations.

      • Lauren S says:

        I tested positive for COVID 19 on 4/2, and had a antibody test 5/15 which was negative via Abbott reliable platform. How is this possible? I am concerned

        • Laura B. says:

          Same situation…. My son in law tested positive April 17, he took the Abbott antibody test on May 20, and he just got an email saying he is negative for antibodies. It is so confusing because we know people who never had any symptoms and tested positive. Stay safe!

        • Nicholas says:

          Same situation here for my parents and their cases were fairly severe.

  • Lauren says:

    I had coronavirus (swabbed positive 4/2) and do not have antibodies.

  • Dobhran C. says:

    I was hellishly sick over the Christmas, until mid Jan. I would get better and feel like going out, then two days later flat non my back again. With no paid sick leave it was a problem. Fortunately I had a bit of back pay from another employer. Full range of symptoms though. Fine now thank goodness.

  • Phil Smith says:

    NEARLY all patients developed antibodies? What about the ones who didn’t? Why not?

  • Anita Broadhead says:

    Can you develop antibodies and still be contagious?

  • Tini says:

    I have been exposed to the virus directly since May 7 and developed no symptoms whatsoever. I’ve taken 2 covid tests that resulted both negative. I’d like to know more about antibodies because how come I’m not developing anything?

  • Laura B. says:

    My son in law tested positive on April 18. He had fever, aches, chills and gastrointestinal issues. No respiratory problems. He was quite ill for 3 days, and then bounced back rather quickly. He had an antibody test on May 20 (so roughly one month after diagnosis) and he tested negative unfortunately. Is it possible he tested too soon after infection? Or perhaps since his case was fairly mild, he didn’t develop antibodies? What a crazy virus!

  • carlybm says:

    Here to echo what my mom, Laura B., said! My husband tested positive for COVID mid April. He thankfully had a very mild case (fever, GI symptoms, severe body aches) that he recovered from quickly. We have spoken to a few doctors in our family and all believe that from a physiological standpoint, everyone should develop antibodies after having any kind of virus. Coronavirus shouldn’t be any different.

    All of that to say, we went to LabCorp yesterday for their IGG antibody test and received results this morning. He tested negative for antibodies. … I’m just curious as to how many other people have tested positive for active infection and then negative for antibodies.

  • Denise Kl. says:

    I tested positive by a throat swab on 4/10/20. I had a mild case of COVID19 with mostly GI symptoms. College students came to our facility and drew blood for antibodies on 5/19/20. My results came back negative for antibodies. How accurate is the antibody test?

  • Eileen E. says:

    My son and daughter in law had Covid, both had positive antibody tests, I was exposed to my son when he was ill, but my antibody test last week of April was negative despite my being ill with fever, cough, palpitations, shortness of breath for 8 weeks or more. I still believe I had this virus. I have never been so sick.

  • Alice N says:

    I went in to get Covid-19 antibody testing done on 5/10 with Sonora Quest Labs as a blood draw which was testing for the IgG antibody. I showed no symptoms of ever having been infected with Covid-19, however, my results came back positive for the antibodies. I went to go get my antibodies tested again 13 days later on 5/23, but this time with Telehealth Consult as a blood test with a finger prick and they were testing for the IgM and IgG antibodies. This was a RAPID result test which provided results in only 5 minutes. My results came back negative for both antibodies. Later that day, I went back to Sonora Quest Labs to have my blood drawn again to get another sample for the Covid-19 antibody test, and got results the following day. It showed that I was negative for the IgG antibody. This indicates 1 of 2 things:
    1. Either the first test was a “false positive” resulting from human error or cross contamination or 2. I’m now testing negative for antibodies because the antibodies for Covid-19 didn’t remain in my immune system for longer than 2 weeks after “supposedly” having been exposed to the Covid-19 virus. I’m led to believe that the first reasoning is a strong possibility explaining my experience and my results from Covid-19 antibody testing.

    • Carly says:

      I think that if you did have covid that antibodies would show up well after two weeks. I’ve read that they’re thinking people will have at least 6 months of antibodies and immunity, maybe more.

      I think it’s more likely the test you took wasn’t accurate. Do you happen to know the brand? My husband tested positive for Corona mid April and then tested negative for antibodies through labcorp‘s antibody test. I know that the labcorp test is an Abbott Diagnostic brand test. Abbott just made headlines for having inaccurate covid tests that look for active infection, so I wouldn’t be surprised if their antibody tests are also inaccurate.

    • Osman (Ozzie) Ahmed, MD says:

      These results make me lose confidence in testing accuracy which could be due to reagents. Strange and can’t be explained on scientific basis.

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