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    Home > Active Ingredient News > Infection > How long does it take for the human body to forget that it has been there?

    How long does it take for the human body to forget that it has been there?

    • Last Update: 2021-08-10
    • Source: Internet
    • Author: User
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    Picture source: Pixabay Recently, Sinopharm and Shanghai Jiaotong University have cooperated to reveal the 12-month changes in the levels of new coronavirus antibodies in patients who have recovered from the new coronavirus infection in Wuhan
    .

    The study included 869 patients who recovered from natural infections in Wuhan, and a total of 1782 plasma samples were collected and analyzed
    .

    The results show that more than 70% of patients who have recovered from natural infection with COVID-19 still maintain positive levels of antibodies in their bodies within 12 months after infection; according to the analysis of plasma samples, the antibody titers of patients who have recovered from natural infections with COVID-19 are in the 9th place.
    It tends to be stable in the next few months
    .

    AuthorYang Xinzhou With the increase in the coverage of the new crown vaccine, many people are concerned about how long the vaccine can provide immune protection
    .

    Because the vaccination time is not long enough, the current academic community cannot fully provide direct evidence to show how long the vaccine is valid
    .

    However, we can look for some data from the side, suggesting the time dimension of individuals in retaining the new crown antibody
    .

    This method has been tried during the SARS period.
    Although there is no SARS vaccine on the market, long-term follow-up of patients and blood samples can be used to understand the persistence of relevant antibodies
    .

    According to existing data, SARS patients can maintain a certain amount of specific antibodies within two years of infection, but the level of antibodies will drop sharply in the third year
    .

    After a year of infection, there are still immune memories.
    So for patients with new coronary disease, is this the same? Some previous studies have found that patients with new coronary disease will produce a large amount of IgM (the earliest antibody after antigen stimulation) and IgG (accounting for 70%-75% of the total immunoglobulin in the blood, and the regression is slower) within a few days of infection.
    The IgM titer reaches its peak in about 10-12 days
    .

    The difference is that the IgG level will continue to rise 3 weeks after the onset of symptoms
    .

    A study in Science in February this year suggested that the receptor binding domain (RBD) of the new coronavirus spike protein will decline after 8 months of infection
    .

    However, the number of memory B cells targeting spike proteins will increase from the first month to the eighth month, and IgG memory B cells still occupy the main position
    .

    According to the conclusion of "Science", 95% of infected people can still maintain the main immune memory for at least six months
    .

    Half a year after infection, the human body can maintain a variety of immune memories, including IgG against RBD, memory B cells, and specific T cells
    .

    (Image source: DOI: 10.
    1126/science.
    abf4063) Can the human body maintain this immune memory for a longer period of time? Recently, there have been a number of studies investigating the changes in antibodies in patients with COVID-19 within 12 months
    .

    One of them was jointly completed by Sinopharm Group and Shanghai Jiaotong University.
    The research published by them in Nature Communications showed that even after 12 months of infection, the survivors still have a certain titre of IgG antibodies against the new coronavirus RBD ( RBD IgG), and in the virus neutralization test, these antibodies can have a neutralizing effect
    .

    Image source: Nat Commun 12, 4144 (2021).
    The study collected 1782 plasma samples from 869 COVID-19 rehabilitation patients from Wuhan.
    These samples were collected in the 12 months after infection
    .

    The study first detected the IgG levels of samples in various time periods.
    In the first two months (pre-phase) after diagnosis, the positive rate of RBD IgG (1:80) was 94.
    6%; and from the 6th to the 7th month (Intermediate), 89.
    4% of samples can still detect RBD IgG; this data will be reduced to 81.
    2% from the 11th to the 12th month (late)
    .

    The study was based on gradient dilutions, setting 1:320-1:640 as medium titer antibodies, and 1:1280 and greater than 1:2560 as high titer antibodies
    .

    According to the test results, the proportions of medium- and high-titer antibodies in the early, mid and late samples were 72.
    6%, 41.
    3%, and 27.
    2%, respectively
    .

    It is worth mentioning that 5.
    4% of the early samples still barely detect RBD IgG, which shows that a small part of the population cannot produce effective antibodies after infection
    .

    From the timeline, within 9 months of diagnosis, the level of RBD IgG antibodies will continue to decline and stabilize after 9 months
    .

    Compared with the antibody titer at the first month, the antibody titer at the 12th month decreased by 69.
    9%
    .

    In addition, those recovering who can produce large amounts of antibodies at the beginning of the infection can also have higher RBD IgG titers at the 12th month
    .

    Image source: Nat Commun 12, 4144 (2021).
    In addition, there are gender differences in the level of RBD IgG.
    Within 12 months of diagnosis, the RBD IgG titer of men is always higher than that of women, especially in the early stage.
    The gap should be more obvious
    .

    At the beginning of the epidemic, there were reports that people with blood type A were more likely to be infected by the new coronavirus, but in this study, people of different blood types did not see significant differences in RBD IgG titers
    .

    A number of studies confirm that there is no coincidence, and the United States University of Health Sciences Uniformed Service has analyzed this
    .

    Simply put, the results are almost the same as the above research, except that there is a special group of people in the United States (people who are infected but not hospitalized) that can be analyzed by additional groups
    .

    In the hospitalized group, 100% of the recovered patients contained COVID-19 antibodies one year after the infection; in the non-inpatient group, 95% and 80% of the patients still had COVID-19 antibodies 6 months and 1 year after infection
    .

    Related research is currently published on the preprinted website medRxiv
    .

    Similarly, in the early stages of infection, the antibody level of the hospitalized population was significantly higher than that of the non-inpatient population
    .

    In follow-up tests, the half-lives of antibodies in the two groups were 88 days and 77 days, respectively
    .

    In the non-hospital population, the antibody level is proportional to the age, and the population older than 65 has the highest level of antibody
    .

    This can also be confirmed in the study of Wuhan population.
    The study of "Nature Communications" also found that the higher the age, the higher the titer of RBD IgG
    .

    In June of this year, Tongji University and Huazhong University of Science and Technology conducted an analysis of a small number of samples of COVID-19 patients.
    According to the research published in "Frontiers in Immunology", a total of 76 patients provided a total of 162 samples
    .

    To be sure, 90% of patients still have RBD IgG after one year
    .

    In this study, it can also be seen that IgM will reach its peak within 1 to 2 months, but it is basically undetectable after a year
    .

    It is still IgG antibodies that can continue to exist stably, and IgG antibodies are basically the same for different individuals from 9 months to 10 months of infection
    .

    However, only 42.
    5% of survivors can show neutralizing antibody activity.
    Studies have shown that even if they have been infected with the new coronavirus, they may still be infected again
    .

    People who are younger than 65 and have experienced mild illness are most likely to have high levels of neutralizing antibody activity
    .

    In addition, the survivors are also very sensitive to the immune response of the new crown mutant.
    The researchers used the serum samples of 53 survivors at the 6th month of the "beta" mutant (the B.
    1.
    351 mutant found in South Africa).
    Neutralization test
    .

    As a result, only 12 samples (22.
    6%) showed neutralizing activity, and only 3 samples (5.
    7%) showed high neutralizing antibody titers
    .

    This means that the original COVID-19 survivor may have little resistance to the mutant strain and will still be re-infected
    .

    The figure on the left shows that the neutralizing activity of the survivor's serum against the mutant strain will be significantly reduced
    .

    (Image source: DOI=10.
    3389/fimmu.
    2021.
    708523) These studies all suggest that our immune system can maintain the memory of the new coronavirus for a long time
    .

    Vaccination with active immunization can activate the immune system, and it can also obtain long-term protection
    .

    Researchers from the Chinese Center for Disease Control and Prevention said in June that existing studies have shown that several domestic vaccines can neutralize multiple mutant strains
    .

    Over time, in the future, there will definitely be studies showing longer-term changes in human neocorona antibodies.
    At this moment, vaccination is definitely the best way to obtain immune protection (it is better than getting immune protection after a wave of infection)
    .

    Reference: https://#citeashttps://science.
    sciencemag.
    org/content/371/6529/eabf4063https:// /10.
    3389/fimmu.
    2021.
    708523/full The July new issue of "Global Science" is now available.
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