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Two Studies Show COVID-19 Antibodies Persist for Months

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Antibodies against SARS-CoV-2
Caption: Artistic rendering of SARS-CoV-2 virus (orange) covered with antibodies (white), generated by an immune B cell (gray) at the bottom left. Credit: iStock/selvanegra

More than 8 million people in the United States have now tested positive for COVID-19. For those who’ve recovered, many wonder if fending off SARS-CoV-2—the coronavirus that causes COVID-19—one time means their immune systems will protect them from reinfection. And, if so, how long will this “acquired immunity” last?

The early data brought hope that acquired immunity was possible. But some subsequent studies have suggested that immune protection might be short-lived. Though more research is needed, the results of two recent studies, published in the journal Science Immunology, support the early data and provide greater insight into the nature of the human immune response to this coronavirus [1,2].

The new findings show that people who survive a COVID-19 infection continue to produce protective antibodies against key parts of the virus for at least three to four months after developing their first symptoms. In contrast, some other antibody types decline more quickly. The findings offer hope that people infected with the virus will have some lasting antibody protection against re-infection, though for how long still remains to be determined.

In one of the two studies, partly funded by NIH, researchers led by Richelle Charles, Massachusetts General Hospital, Boston, sought a more detailed understanding of antibody responses following infection with SARS-CoV-2. To get a closer look, they enrolled 343 patients, most of whom had severe COVID-19 requiring hospitalization. They examined their antibody responses for up to 122 days after symptoms developed and compared them to antibodies in more than 1,500 blood samples collected before the pandemic began.

The researchers characterized the development of three types of antibodies in the blood samples. The first type was immunoglobulin G (IgG), which has the potential to confer sustained immunity. The second type was immunoglobulin A (IgA), which protects against infection on the body’s mucosal surfaces, such as those found in the respiratory and gastrointestinal tracts, and are found in high levels in tears, mucus, and other bodily secretions. The third type is immunoglobulin M (IgM), which the body produces first when fighting an infection.

They found that all three types were present by about 12 days after infection. IgA and IgM antibodies were short-lived against the spike protein that crowns SARS-CoV-2, vanishing within about two months.

The good news is that the longer-lasting IgG antibodies persisted in these same patients for up to four months, which is as long as the researchers were able to look. Levels of those IgG antibodies also served as an indicator for the presence of protective antibodies capable of neutralizing SARS-CoV-2 in the lab. Even better, that ability didn’t decline in the 75 days after the onset of symptoms. While longer-term study is needed, the findings lend support to evidence that protective antibody responses against the novel virus do persist.

The other study came to very similar conclusions. The team, led by Jennifer Gommerman and Anne-Claude Gingras, University of Toronto, Canada, profiled the same three types of antibody responses against the SARS-CoV-2 spike protein, They created the profiles using both blood and saliva taken from 439 people, not all of whom required hospitalization, who had developed COVID-19 symptoms from 3 to 115 days prior. The team then compared antibody profiles of the COVID-19 patients to those of people negative for COVID-19.

The researchers found that the antibodies against SARS-CoV-2 were readily detected in blood and saliva. IgG levels peaked about two weeks to one month after infection, and then remained stable for more than three months. Similar to the Boston team, the Canadian group saw IgA and IgM antibody levels drop rapidly.

The findings suggest that antibody tests can serve as an important tool for tracking the spread of SARS-CoV-2 through our communities. Unlike tests for the virus itself, antibody tests provide a means to detect infections that occurred sometime in the past, including those that may have been asymptomatic. The findings from the Canadian team further suggest that tests of IgG antibodies in saliva may be a convenient way to track a person’s acquired immunity to COVID-19.

Because IgA and IgM antibodies decline more quickly, testing for these different antibody types also could help to distinguish between an infection within the last two months and one that more likely occurred even earlier. Such details are important for filling in gaps in our understanding COVID-19 infections and tracking their spread in our communities.

Still, there are rare reports of individuals who survived one bout with COVID-19 and were infected with a different SARS-CoV-2 strain a few weeks later [3]. The infrequency of such reports, however, suggests that acquired immunity after SARS-CoV-2 infection is generally protective.

There remain many open questions, and answering them will require conducting larger studies with greater diversity of COVID-19 survivors. So, I’m pleased to note that the NIH’s National Cancer Institute (NCI) recently launched the NCI Serological Sciences Network for COVID19 (SeroNet), now the nation’s largest coordinated effort to characterize the immune response to COVID-19 [4].

The network was established using funds from an emergency Congressional appropriation of more than $300 million to develop, validate, improve, and implement antibody testing for COVID-19 and related technologies. With help from this network and ongoing research around the world, a clearer picture will emerge of acquired immunity that will help to control future outbreaks of COVID-19.

References:

[1] Persistence and decay of human antibody responses to the receptor binding domain of SARS-CoV-2 spike protein in COVID-19 patients. Iyer AS, Jones FK, Nodoushani A, Ryan ET, Harris JB, Charles RC, et al. Sci Immunol. 2020 Oct 8;5(52):eabe0367.

[2] Persistence of serum and saliva antibody responses to SARS-CoV-2 spike antigens in COVID-19 patients. Isho B, Abe KT, Zuo M, Durocher Y, McGeer AJ, Gommerman JL, Gingras AC, et al. Sci Immunol. 2020 Oct 8;5(52):eabe5511.

[3] What reinfections mean for COVID-19. Iwasaki A. Lancet Infect Dis, 2020 October 12. [Epub ahead of print]

[4] NIH to launch the Serological Sciences Network for COVID-19, announce grant and contract awardees. National Institutes of Health. 2020 October 8.

Links:

Coronavirus (COVID-19) (NIH)

Charles Lab (Massachusetts General Hospital, Boston)

Gingras Lab (University of Toronto, Canada)

Jennifer Gommerman (University of Toronto, Canada)

NCI Serological Sciences Network for COVID-19 (SeroNet) (National Cancer Institute/NIH)

NIH Support: National Institute of Allergy and Infectious Diseases; National Institute of General Medical Sciences; National Cancer Institute

50 Comments

  • Randolph W. says:

    Tested positive for coved 19 July 15, Tested negative August 18, I have donated plasma 5 times since. All antibodies tested positive as of January 6. My question is: Do I reduce my resistance to covid 19 by donating plasma?

    • Mrs. C says:

      No, sir, the cells that produce antibodies are returned to your bloodstream during the process of plasmapheresis, where they will continue to do their job of making antibodies. I donated plasma only a couple of times after recovering from COVID myself and the process was explained to me in detail. You are protected and, in my humble opinion, you won’t get sick with it again, Welcome to the herd!

    • Sue Lynn J. says:

      I’m in Indiana and I have antibodies to covid when tested 3 weeks ago. today is the 25th March 2021.
      I feel great except for kidney stones too much tea ha!
      I was hospitalized Oct 7th 2020 I was in hospital for 6 days really bad then I was released feeling much better but I had pneumonia last week of Sept 2020
      Please help me to understand if I’m not going to get it again or just that I had immunity for longer periods than millions of people

  • Debbie says:

    I suffered from Covid in Mar/ Apr last year and was very ill but recovered. I have done two antibody tests one in Oct 20 and one in Dec 20 both tests still show I have the antibodies. Is this a good thing and is it unusual to have these so long after the infection?

    • rxstafford says:

      Debbie, I have antibodies after a year of having COVID, which no one knew I had because COVID wasn’t on the radar yet. I think antibodies last far longer than many people believe, and they’re valuable things to have. Congratulations!

  • Sigrid E. says:

    I contracted covid19 in mid June of 2020 without any known symptoms other than a racing heart at night and panic attacks. That condition persisted for about 6 weeks with no cough no fever and without the knowledge of the infection. In mid July, I was tested for covid and quarantined for 20 days following my doctor’s order.
    I was going about my life for 4 weeks without knowing of my infection and always wondered if the quarantine order was too late ore useless.
    In any case, I had a very bad case also due to my COPD, but managed to stay out of the hospital. Not getting much help from my doctor and so much confusing information from the CDC, I just followed my own common sense. Hydration, rest with intermittent exercise to keep the lungs working, 800 mg of Ibuprofin to fight inflammation 400 mg am and 400 mg pm. by 2 , Vit C, Zink.
    In mid August I still tested positive, although in late Aug. beginning of September, I felt I was getting better, getting out of bed, preparing a meal and going for quick shopping trips.
    I started lap swimming every day and thought I had beaten it.

    Sometime in October/ November, I started experiencing strange symptoms: a foggy brain and tremendous fatigue attacking also my legs. These symptoms appeared quite frequently during the day with deadening feelings throughout my head and my entire body. I had also gaps in my memory trying to think where this and that was in my home. I went to see a neurologist and the tests he prescribed came back normal. My lung function test checked out perfect.

    Later I visited my cardiologist because I have some existing problems in my vascular system. Venous reflux and some plaque in the legs’ arteries, that was previously not considered troublesome and to be treated with exercise. These new ultrasounds of heart, venes and arteries, however, showed now severe stenosis in my right leg and some in the left. Heart muscle strong.

    I sought out a holistic approach for all my symptoms and had acupuncture, once a week for 5 months.I did improve my health tremendously and am still sticking with the Acu, certain vitamins, esp. Vit B6, Qi Gong, especially for correct breathing exercises.

    About 3 weeks ago, I was tested for antibodies and had indeed
    the good kind (igG) which is supposedly the one, that keeps one a bit longer immune.
    I will, in another two or three months,
    retest.

    At this point in my ordeal, I am basically waiting to get normal again, but have read that some patients may never be able to rid themselves of this what the CDC called “post viral symptoms.”

    With this detailed info of my course of the Corona virus infection, I am hoping to help some of you to learn how different everybody is and what to do. Nobody even in the medical field really knows much more than what maybe after 3 months of immunity.

    I do wish that hydroxychloroquine would not have got such bad report, because ( a common drug for certain immune disorders) it would have helped, as is now reported , many of us to recover more quickly and possibly fully and may have prevented so many deaths.

    • anam says:

      Thanks for your comment.

    • rxstafford says:

      Thanks for sharing this difficult experience. As you see, you raise issues that seem to fall into the category of politically incorrect. A sad comment on our times. I trust you will regain your health and strength fully. Take very good care.

  • T Williams says:

    My family and I all had covid at the end of April last year. We have all tested positive for antibodies this past week (2/10/21). YES!!

  • Ralph H. says:

    After discovering I had cover-19 I was hospitalized for two weeks. I spent 12 days in the ICU and the doctors paid close attention to my oxygen intake. Its been 5 weeks since I was discharged with no apparent symptoms. I had covid-19, pneumonia, and a blood clot. Doctors told my wife after two days I had a better chance of dying than living. I lost 10 pounds but regained that and some since coming home. My wife also contracted the disease but had less problems than me. We are wondering if we should get shots.

  • Rosa R. says:

    I have covid19 positive on march last year i have antibody and still positive for covid19

    • Nancy says:

      I also had Covid-19 March 2020 (It’s a year today). My recent lab results of a few days ago, still show I have the antibodies. Goes to show the science world still doesn’t have enough information for me to get the vaccine.

  • DEBRA B. says:

    I had Covid-19 in March 2020 quite mildly. I did an antibodies test a few weeks ago and it tested positive for igG and igM. I was relieved to find out I still had antibodies after all this time and after only having a mild infection. Now I have read that a positive igM result means I must have had an infection quite recently if I still have the antibodies. This has worried me slightly as I was not aware I had had another infection or where I have been to get one.
    My test did not show levels of each antibody so does anyone know if I could still have very low levels of igM a year later?

    • Mom2four says:

      I’m reading the paperwork that came in my test results, and it’s saying these results can be false negative and false positives. CVS charges forty dollars to get tested. I’d just get tested again in a month.

  • Julles in Manhattan says:

    Hi all. I am a 51 y/o female living in Manhattan. I am a first-responder frontline healthcare worker. I am a nurse anesthetist, which means I give anesthesia for a living but I am a nurse, not a doctor. Before the pandemic started, I would intubate patients for surgery and put breathing tubes in as part of my normal job. When the pandemic hit, all elective cases canceled. We were sent to the Covid ICUs to help the physician assistants (PAs) and the critical care physicians with the overwhelming patient load. I moved out of our apartment and into a hotel for almost 2 months as I did not want to risk exposing my son to the virus. He is 9 and had heart surgery at age 6. Plus, my husband has asthma so they were both considered high risk.

    It was a living nightmare every day. We ran out of bodybags. They were all SO sick. The patients were dying left and right. The morgue was overflowing. Refrigerated 18 wheeler trucks were storing them because there was no place else to put them. One day the central oxygen supply ran out because so many patients were on ventilators. Patients who weren’t dying from pneumonia were dying from horrible strokes and clots.

    I sort of assumed going into this crisis last March 2020 that I was bound to contract it myself because of all my exposure. I tested negative for antibodies through the blood test in May 2020. I quarantined at the hotel, packed up and came back to my family. Fast-forward to December 2020. We went to visit family in the South. I contracted Covid there at a party on my husband’s side of the family. His nephew’s wife had Covid, but now had no symptoms after more than 3 weeks. Her husband swabbed negative. Their baby was not sick. We thought we were in the clear. Four of us contracted the virus from that party and four others who were there at the same party did not. I was exposed Jan 1st, symptoms started late in the day on Jan 4th. The headaches, temps over 101.5, muscle aches and pains were the early symptoms. I lost smell and taste but it was a late symptom. I was getting my nasal PCR swab done on Jan 6th as our nation’s capitol was being attacked. I later had weird symptoms like the soles of my feet peeled off in big sheets (ewwww – i know). My sense of smell and taste left for a while, briefly returned, and left again!

    I got my antibodies drawn and they were positive on Feb 1st. I had them drawn again through work March 5th and still positive. Three of my doctors advised me to wait at least 90 days from onset of symptoms to get the vaccine. I have friends who still have antibodies almost one year after their initial infections.

    For anyone questioning if Covid is really worse than any other diseases like the flu: YES it most certainly is.

  • Christine says:

    I tested positive in November 2020. I have tested every month since for antibodies. I have had IGG and IGM since then. I tested last week 3-18-21. Everything I have read said that IGM goes away quickly. What would be the reasoning that IGM is still showing up. I have no symptoms and have not to my knowledge been exposed again.

  • Rita S. says:

    I was sick early February 2020 but tested negative for the flu. Over a year later, in late February 2021 I tested positive for COVID antibodies. I have never been sick since February 14, 2020. My COVID antibodies appear to be long lasting, and I have developed an affection for them. Would the vaccine alter them in any way? I do not want to compromise them. My doctor inferred I may have immunity but recommends I take the vaccine anyway. Is the single J&J Janssen vaccine better in a situation such as mine?

    • Mom2four says:

      I’m not going to give my opinion, but rather plead with you to do your own research before you get a vaccine after building up natural immunity. You’ll feel much more confident in your decision.
      Also, remember what we’ve been taught in school and by our doctors BEFORE Covid about how our immune systems and vaccines work. Covid may be different, but our immune systems are not. Best wishes!

  • ryan says:

    NYC ICU nurse here – seeking some clarification and thankful for all your expertise! Never tested positive but had positive antibodies beginning of April 2020 subsequently donated 3 times in April, May, and June of 2020. Persistent SOB only symptom. Since then at my job I’ve tested positive for antibodies (never positive swab/saliva) each month since June 2020; most recently I’ve been positive for Quantitative Antibody 4/5/21. My initial antibody titer, which I was told done as an ELISA, was 2880 performed on 4/6/20. Since its a year out is it fair to say that I had a high enough viral load/titer that I will not contract this virus again and therefore hold on the vaccine? (I am hesitant for personal reasons). Thank you again for your time and insight.

  • Linda says:

    Giving blood at Red Cross I tested positive for antibodies August 2020. I am still positive April 2021. I had no symptoms of Covid. I received 2 Moderna vaccines but They aren’t showing reactive on Red Cross test.

  • Dawn says:

    I tested positive on June 30 and negative on July 18, 2020..
    I have my antibodies checked every other month and I still have them almost 11 months later. I’m January I also had IgM antibodies along with normal IgG. They told me that suggested that I had been exposed again but my IgG antibodies had protected me from getting g COVID. I am assuming once you have the antibodies, you will always have them.

  • judy g says:

    I had Covid-19 back in December 2020. It was a very mild case. I just had a cough. I got tested and I was positive. I waited three weeks before testing for antibodies. My blood work showed I had antibodies. My internist told me not to get the vaccine because I had plenty of antibodies and that is what the vaccine gives you. I now took blood work in June 2021 and showed I had 89 antibodies which my doctor said was good. He again said do not take vaccine now. Come back in 3 months and do blood work again and we will go from there. He stated that I may have immunity for the rest of my life. The scientists are studying this right now. The problem is I want to see my six year old Granddaughter so he said come in for the covid-19 nasal test a few days before I visit her to make sure I am not a carrier. Makes sense I think.

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