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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

18 Comments

  • Joseph says:

    They left out the T cell response.

  • Lisa Phillip Rimland says:

    Thank you for posting, and for your clear explanations of these studies. As our understanding of Covid increases, so does our hope for the future.

  • R.obert F.ranklin Smith says:

    Thank you! This is very timely (and very welcome) news. I do hope with this funding our NIH will continue with longer term antibody research (18-30 months seems appropriate). Best wishes, Rob Smith

  • Martha Price says:

    Back-tracing evidence as well as visits to my physician’s office for symptoms, indicate that I developed COVID-19 symptoms on or about December 23, 2019, having been exposed to the virus on December 17. I was not supported to be tested for antibodies until May 20, at which time I tested positive via the Mayo Clinic lab. I re-tested on July 10, (then seven months after developing symptoms), via my local hospital lab, and again tested positive. At the end of September, I tested at LabCorp, and the result was negative. There have been many strange neurological symptoms, all but three which have finally subsided. Cardiac arrhythmia developed in December on the very same day that I developed a dry cough, and palpitations still continue, though less frequently. Documenting my symptoms daily since December, I eagerly read the research reports regarding all aspects of Covid-19.

  • Byron Mui says:

    This is good news. Since reinfection with SARS-COV-2 is rarely reported, it would be interesting to see if the T-cell immune response does play a role to prevent reinfection.

  • Michael N. Alexander says:

    The article suggests that monitoring IgG antibodies may be useful in tracking Covid-19. Are the antibodies in question unique to Covid-19, or could other conditions provoke their appearance?

  • Billy A. says:

    I tested positive june 7 until june 30.. It’s now Oct. but still have loss of taste and started getting weak very fast. Dr – Left ventricle enlarged, white, red, thyroids, platelets all very good.. Trying to find out why loosing energy and blood pressure dropping out of sight ?? 57 and not overweight, very fit but gaining weight. Drs have nothing so hoping to find something on this website to start me down some path to what’s going on…

  • John C. says:

    I tested positive for Cov March 15 2020. Lasted about 10 days with a low grade fever along with being super tired. 5 days of antibiotics helped the symptoms and my recovery. Took an antibodies test Oct 20 2020 and it came back positive for the antibodies from a Cov infection.
    It’s hard to describe lasting symptoms because these are not normal psychological times however I do have some brain fog some days and get tired. Working out helps and resting when tired is the best medicine.

  • Jay T says:

    My question and comment in regards to how many antibodies, especially IgG (long term or lasting antibodies), are produced per each antigenic covid-19 virus. What is the ratio of the production or replication of natural antibodies to each virus? 100 to 1? 1,000 to 1? or is it 10,000, or even 100,000, or more; ensuring adequate circulating antibodies, actual immunity, for any return bio-identical virus in the future to the same host. Decades ago physiologic studies stated that a healthy human male produced on average 400 million sperm on ejaculation for the purpose of a single sperm penetrating a single human female egg (ovum).Was perpetuation of our specie ever that desperate?Would the enormity of sperm production to perpetuate our specie, also be repeated in antibody production in an innate motive of protecting the life of a single member of our specie, the individual host, a covid-19 patient, if in fact Covid19 virus is lethal? In the cases of lifetime immunity with childhood diseases, e.g., of measles, mumps, and chicken pox, wouldn’t there be also an innate motive for lifetime immunity in the case of life threatening Covid-19 infection? Since upper 90 percentile of people contracting Covid-19 virus result in zero to mild symptoms, could the Covid-19 virus be just another seasonal flu and not lethal, instead the blame for lethality be placed on the patients’ pre-existing conditions, plus the added burden of the toxicity of their prescription drugs? Should this be anywhere near the case, or even otherwise, could the the Covid-19 virus itself actually be non-lethal?

  • TW Stewart says:

    Can this finding help with the development of a vaccine?

  • abishek says:

    The information is useful …

  • Tony Ross says:

    I can’t help but wonder if regular exposure to the virus would extend immunity for those who experienced symptomatic covid and recovered? If immunity results from exposure, ie from the body’s response, would it decrease if repeatedly exposed following the initial exposure? Why would regularly exposing those who have recovered with controlled amounts of the virus be a risk?

  • William H. says:

    Going on 5 months now of positive Antibodies. Getting tested every month at my expense as a personal study. We will see how long they last!

  • Colleen Sohmer says:

    As a 23 year veteran RN in NYC and a Covid19 survivor, this is so encouraging to hear! I’ve done my own monitoring with my antibodies and I’m still positive for IgG antibodies after 8 months. I’ve tested for antibodies 3 separate times since May of 2020. First symptom 3/16/20 with 1st PCR test negative on 3/30/20. Symptoms seemed to improve after a week or so then became worse again with PCR testing positive 4/8/20. I continued to have symptoms through mid May & June.
    My first positive IgG antibody test was on May 1st, then again in August and now November 4th it was positive again. So I’d say that’s promising!

    • nick D says:

      Had covid early March. Antibody positive in May blood test. Had blood work in November with another antibody test. Still positive for the antibody.

      • Tony R. says:

        Wife and I had it in the beginning of July. Tested positive for antibodies 2 weeks ago. Evidence is mounting that antibodies last and prevent reinfect ion in vast majority of cases. Also, number of confirmed of infections is minute and infinitesimal as a percentage of known cases, forget unknown cases. Obviously, no guarantees, but I like the odds. I do wonder why they don’t develop some sort of regular re-exposure protocol for those who have had it in order to maintain levels of antibodies, T cells etc. Like a nasal spray containing the virus or form of it. A nasal booster vaccine of sorts …

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