How long is antibody duration in Covid 19 ? / Antibodies

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How long is antibody duration in Covid 19 ? / Antibodies

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How long is antibody duration in Covid 19 ? / Antibodies

Studies Report Rapid Loss of COVID-19 Antibodies

https://www.the-scientist.com/news-opin ... dies-67650

The results, while preliminary, suggest that survivors of SARS-CoV-2 infection may be susceptible to reinfection within weeks or months.
By
Amanda Heidt
Jun 19, 2020

A pair of studies published this week is shedding light on the duration of immunity following COVID-19, showing patients lose their IgG antibodies—the virus-specific, slower-forming antibodies associated with long-term immunity—within weeks or months after recovery. With COVID-19, most people who become infected do produce antibodies, and even small amounts can still neutralize the virus in vitro, according to earlier work. These latest studies could not determine if a lack of antibodies leaves people at risk of reinfection.

One of the studies found that 10 percent of nearly 1,500 COVID-positive patients registered undetectable antibody levels within weeks of first showing symptoms, while the other of 74 patients found they typically lost their antibodies two to three months after recovering from the infection, especially among those who tested positive but were asymptomatic.

In contrast, infections caused by coronavirus cousins such as SARS and MERS result in antibodies that remain in the body for nearly a year, according to The New York Times.

The first study, published June 16 on the preprint server medRxiv, screened for antibodies in almost 1,500 coronavirus patients in Wuhan, China. The researchers compared their levels to three other groups: nearly 20,000 members of the general population; more than 1,600 patients hospitalized for reasons other than COVID-19; and more than 3,800 medical workers, whom the authors assumed had “inevitably” been exposed to the virus in its early days, meaning they should have developed antibodies.

They found that while almost 90 percent of COVID-19 patients had antibodies, roughly 1 percent to 5 percent of individuals in the others groups had them as well. The authors conclude in their paper that the remaining 10 percent of infected patients with no detectable antibodies, combined with the lack of antibodies in healthcare workers, suggest that “after SARS-CoV-2 infection, people are unlikely to produce long-lasting protective antibodies against this virus.”


In the second study, published June 18 in Nature Medicine, researchers compared the immune responses of 37 asymptomatic but positive patients to an equal number with severe symptoms living in the Wanzhou District in China. They found that asymptomatic individuals reacted less strongly to infection, with 40 percent having undetectable levels of protective antibodies in the two to three months after the infection compared to 13 percent of the symptomatic patients.

“Overall, these results are interesting and provocative but more research is needed, following large numbers of people over time,” Daniel Davis, an immunologist at the University of Manchester, tells Newsweek. “Only then will we clearly know how many people produce antibodies when infected with coronavirus, and for how long.”

The discrepancies between people mirror what Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, has himself observed. In a conversation with Howard Bauchner, the editor in chief of the Journal of the American Medical Association earlier this month, he said that in addition to a lack of consistency among testing methods, individuals do not have “a uniformly robust antibody response.” This fact may make it difficult to develop a vaccine that works equally well for all people.


“These reports highlight the need to develop strong vaccines, because immunity that develops naturally during infection is suboptimal and short-lived in most people,” Akiko Iwasaki, a viral immunologist at Yale University who was not involved in either study, tells The New York Times. “We cannot rely on natural infection to achieve herd immunity.”
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Re: How long is antibody duration in Covid 19 ?

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There have been untold numbers of re-infection and that may be where you find the next mutation(s).
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Re: How long is antibody duration in Covid 19 ? / Antibodies

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Rapid Decay of Anti–SARS-CoV-2 Antibodies in Persons with Mild Covid-19

9/10/20

https://www.nejm.org/doi/full/10.1056/nejmc2025179
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Re: How long is antibody duration in Covid 19 ? / Antibodies

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Investigation of SARS-CoV-2 antibody responses in patients with aggressive hematological malignancies

10/4/20


https://www.news-medical.net/news/20201 ... ncies.aspx


Patients with hematological malignancy (PHM), also infected with COVID-19, were investigated for SARS-CoV-2 antibody responses while undergoing systemic anti-cancer therapy. While no obvious correlation is found between the serological results and the hematological diagnosis and the treatment, the immune response is similar to the severity of COVID-19 infection observed in the general population.

According to WHO reports, the current COVID-19 (coronavirus disease 2019) pandemic has caused more than 35 million COVID-19 positive cases, with over 1 million deaths. COVID-19 is caused by SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), a novel coronavirus strain. It is essential to understand the immune response caused by SARS-CoV-2 in patients to develop strategies for effective preventive measures, successful therapies, and to increase the recovery rate. Immune responses may vary significantly, as observed in the presence of comorbidities.

Underlying diseases, like cancer, are a high risk-factor during COVID-19 infection. Cancer patients may present severe complications due to their malignancy, specific immune responses, and therapy-related issues. In a new study published on the medRxiv*, Jenny O’Nions et al. investigate SARS-CoV-2 antibody responses in a cohort of patients with both aggressive hematological malignancies and COVID-19, at University College London Hospital.

Patients with hematological malignancy (PHM) constitute only 10% of all cancers; however, their therapeutic management in the face of a pandemic becomes complex. PHM are reported to have severe outcomes during COVID-19 infection. High-mortality is also observed, leading to a need for changes in standard therapies. Most of the prevalence, clinical course, and outcomes of COVID-19 in PHM is not yet fully established.

Several recommendations have been made to the standard therapies for PHM to address the COVID-19 infection and mitigate it. Towards this effort, the study of immune responses towards SARS-CoV-2 in PHM is underway. However, the seroprevalence and the magnitude, kinetics, and functionality of the antibody response in PHM are not known. In this study, serum from 10 patients with aggressive hematological malignancies and COVID-19 was collected between April and May 2020 and tested for antibodies against the viral antigens.

All patients received SACT (systemic anti-cancer therapy) within 28 days of developing COVID-19 infection. The COVID-19 symptoms in these patients were mild to severe, with 2 of them requiring ITU (intensive therapy unit) and mechanical ventilation. Post-treatment, all patients were discharged from the hospital within ~22.5 days of illness. All the patients tested positive for SARS-CoV-2 RNA by PCR (polymerase chain reaction) method, except for one patient.

Serum samples were screened for anti-SARS-CoV-2 antibodies - against the external Spike (S) protein antigen and the Nucleoprotein (N) antigen. Two patients exhibited serum negativity. Total serum IgG was also normal in each case, confirming that any reduction or absence of SARS-CoV-2 IgG was not due to hypogammaglobulinemia (indicating an impaired immune system). The authors demonstrate that PHM can generate antibodies to SARS-CoV-2 antigens, similar to other COVID-19 patients without hematological malignancy.

The authors also compared the temporal dynamics of SARS-CoV-2 antibody responses: seroconversions to both antigens (S and N) were similar to those reported in patients without hematological malignancies, with a slight delay.

Further, to test the functional activity of SARS-CoV-2-specific antibodies - to inhibit SARS-CoV-2 infection and to neutralize the virus - the researchers assessed the neutralization activity (in vitro) of sera from the patients. As expected, the seronegative patients showed no neutralization activity; however, in six of the eight seropositive patient samples, the viral infection is inhibited. The two patients who showed no neutralization activity had very low anti-S1 IgG levels, almost in unquantifiable levels. S1 is the domain of the spike antigenic protein of SARS-CoV-2. It is interesting to note, however, that two other patients, despite low anti-S1 IgG levels, neutralized the infection successfully. The researches explain the cause of this unique observation in patients: (i) they produced a relatively high proportion of S1- specific IgG with neutralizing capacity, (ii) they produced low titers of particularly potent antiS1 IgG, (iii) they produced neutralizing antibodies directed against other viral epitopes, or (iv) they produced non-IgG neutralizing antibodies.

Also, the authors note that the patients with the strongest anti-S1 IgG and neutralizing responses were generally the most severely ill. This is not absolute, however, they point out. In this study, the authors report the first longitudinal study of serological responses to SARS-CoV-2 in adult patients undergoing SACT for aggressive haematological malignancies. The magnitude of the observed antibody response generally correlates with the severity of COVID-19, as is reported in the general population. These observations needed to be studied in larger cohorts of patients to draw conclusions and modify the approach to such cases.

They conclude that there is no apparent correlation between serological response and hematological diagnosis, type, or intensity of SACT. The time for seroconversion however, is consistently longer in PHM. This study highlights the complexity in establishing causes of the variable responses observed and the need to understand better the quality of antibody responses in PHM with different diagnoses and therapies.
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Re: How long is antibody duration in Covid 19 ? / Antibodies

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Less than 10% of US adults have SARS-CoV-2 antibodies

10/5/20


https://www.news-medical.net/news/20201 ... odies.aspx


A new study by researchers at Stanford University and Ascend Clinical Laboratory and published in the journal The Lancet in September 2020 reports the prevalence of antibodies to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus in a dialysis patient population in the US.

Advantages of the Sample

The researchers selected this population since these patients are tested every month to monitor their therapy and detect complications. This makes it easy to test for seropositivity to this virus without the need for another venepuncture since the dialysis port is in place. Moreover, these individuals typically have the risk factors that are considered to increase the risk of infection and severe COVID-19, including older age, non-white race, poverty, and diabetes, at a far higher frequency than in the rest of the US population. Thus, testing this population for seroprevalence using remainder plasma was considered a population-representative surveillance strategy that can be maintained longitudinally.

Study Characteristics

The researchers tested a randomly selected group of dialysis patients, aiming to arrive at an estimate of national exposure to SARS-CoV-2 in the period from the beginning of the pandemic to July 2020, by age, sex, region, and race.

The study included over 28,500 individuals, with the majority being tested in the first two weeks. The study also uses case testing data (nasal swab testing by a polymerase chain reaction, PCR), that can help to evaluate the correlation between seroprevalence and other measures of the pandemic such as the number of cases, deaths, percentage of positive tests, and community-based risk factors for seropositivity.

Less than Ten Percent Seropositivity

Overall, 8% of the tests were positive for antibodies. The highest seroprevalence was in the northeast, at ~27%, and the lowest in the south, at ~4%. There was no difference between males and females, but there was a slight drop in patients above 80 compared to those aged 45-64 years. The former were 20% less likely to be seropositive.

When classified by race, non-Hispanic Black patients were 2-3 times more likely to be seropositive, and non-Hispanic white patients the least.

Based on data from June 2020, the prevalence of PCR positive cases is estimated to be 826/100,000 US adults. In contrast, the current seroprevalence estimate is almost 9,000/100,000 population, indicating that only less than one in ten seropositive people are being picked up during the period of infection – despite the fact that the highest number of confirmed cases in the world is in the US at present.

On the other hand, a 9% seroprevalence indicates that most American adults are still free of the virus. This includes dialysis patients who have one of the highest risk levels for COVID-19-related mortality in the world.

Poor Correlation with Other Measures

The highest variation between estimates was in New York, at ~34%, but seven states had zero variation. The best correlation was with the measure of cumulative deaths per 100,000 population. People from more impoverished neighborhoods had twice the risk, while those from crowded areas had a tenfold risk. The mobility-restrictive measures implemented in March of this year reduced seroconversion rates by 60%, it was found.

Possible Limitations


The study presents robust data since the samples were collected on a routine basis, eliminating numerous sources of bias, unlike most other studies. On the other hand, the seroprevalence in the dialysis group may overestimate the community prevalence for several reasons.

One, this group contains a higher proportion of poorer and ethnic-minority individuals. Black Americans are known to have a fourfold risk of end-stage kidney disease compared to whites. Secondly, the patients might use shared transport to reach the center for hemodialysis, as well as being in the center for 10-12 hours each visit, both of which could promote higher transmission.

On the other hand, dialysis patients are less likely to be working and more likely to be confined to home, thus reducing transmission chances. And finally, seroconversion may be weaker in these patients, due to a weaker immune response, as seen in studies on hepatitis B immunization in this group, where only up to 75% of vaccinated individuals seroconverted vs 95% in the general population.

Another confounding factor is the possible absence of the most seriously ill SARS-CoV-2 patients in the dialysis group because of death or hospitalization with other indications, thus ensuring their exclusion from the dialysis group.

Implications


The estimated seroprevalence is in agreement with those from earlier studies, both in the US and in Geneva, Switzerland, and shows that less than a tenth of Americans has been exposed to the virus by July 2020. Thus, herd immunity is still a distant dream, despite the large outbreaks in the first part of the year, just as is seen with other extensive seroprevalence surveys in the similarly hard-hit UK and Spain.

The study also highlights the disparities in healthcare among ethnic, racial, and socioeconomic groups, which have become further exaggerated with the current pandemic. The tenfold risk of seroprevalence among those living in high-density areas as in crowded cities, confined spaces, and large gatherings as in carnivals, shows the essential nature in the viral spread.

The somewhat lower odds of seropositivity among older people could be because they are more careful to keep a distance from other potentially infectious people, but it is not possible to rule out the chance that more older people might be hospitalized or have died of the infection, thus excluding them from the sample group in this study.

Given these factors, the study provides a model for community surveillance of the pandemic and highlights the feasibility and cost-effectiveness of using repeatedly collected routine collected samples from a group of individuals already undergoing monitoring to fully measure the true incidence of SARS-CoV-2 infection and complement more rapid and limited surveys. The accuracy of this estimate is shown by the lack of correlation between this and other currently used measures of prevalence, except for cumulative deaths, to some extent.

Such surveys can also help to evaluate the adequacy of testing, and the longitudinal follow-up may predict hospitalizations and ICU admissions, given the short 10-day gap, on average, between exposure and seroconversion. This helps with preparedness measures. They can also help assess how well preventive and therapeutic interventions work. And all of these benefits arrive at a little additional cost as remainder plasma is used, obviating the need for venepuncture with the requirements for staff, equipment and infrastructure, while including groups that are traditionally left out or under-represented.

The study includes, “Serial sampling of dialysis remainder plasma should be used to determine trends in disease prevalence and the effect of various strategies being implemented around the USA to reduce the burden of COVID-19 on the general population.”
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Re: How long is antibody duration in Covid 19 ? / Antibodies

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People who survive serious COVID-19 infections have protective antibodies for months

10/9/20


https://www.news-medical.net/news/20201 ... onths.aspx

People who survive serious COVID-19 infections have long-lasting immune responses against the virus, according to a new study led by researchers at Massachusetts General Hospital (MGH).

The study, published in Science Immunology, offers hope that people infected with the virus will develop lasting protection against reinfection. The study also demonstrates that measuring antibodies can be an accurate tool for tracking the spread of the virus in the community.

The immune system produces proteins called antibodies in response to SARS-CoV-2, the virus that causes COVID-19.

" But there is a big knowledge gap in terms of how long these antibody responses last."

-Richelle Charles, MD, Study Senior Author and Investigator, Division of Infectious Diseases, Massachusetts General Hospital

To find out, she and her colleagues obtained blood samples from 343 patients with COVID-19, most of whom had severe cases. The blood samples were taken up to four months after a patient's symptoms emerged.

The blood's plasma was isolated and applied to laboratory plates coated with the receptor-binding domain (RBD) of the virus's "spike" protein, which attaches to cells, leading to infection.

The team studied how different types of antibodies in the plasma bound to RBD. The results were compared to blood samples obtained from more than 1,500 individuals prior to the pandemic.

The researchers found that measuring an antibody called immunoglobulin G (IgG) was highly accurate in identifying infected patients who had symptoms for at least 14 days.

Since the standard PCR (nasal swab) test for SARS-CoV-2 loses sensitivity over time, augmenting it with a test for antibodies in patients who have had symptoms for at least eight days (at which time 50 percent are producing antibodies) will help identify some positive cases that might otherwise be missed, says Charles.

The researchers found that IgG levels remained elevated in these patients for four months, and were associated with the presence of protective neutralizing antibodies, which also demonstrated little decrease in activity over time. "That means that people are very likely protected for that period of time," says Charles. "We showed that key antibody responses to COVID-19 do persist."

In another finding, Charles and her colleagues showed that people infected with SARS-CoV-2 had immunoglobulin A (IgA) and immunoglobulin M (IgM) responses that were relatively short-lived, declining to low levels within about two and a half months or less, on average.

"We can say now that if a patient has IgA and IgM responses, they were likely infected with the virus within the last two months," says Charles.

Knowing the duration of the immune response by IgA and IgM will help scientists obtain more accurate data about the spread of SARS-CoV-2, explains Jason Harris, MD, a pediatric infectious disease specialist at MGH and co-senior author of the study.

"There are a lot of infections in the community that we do not pick up through PCR testing during acute infection, and this is especially true in areas where access to testing is limited," he says. "Knowing how long antibody responses last is essential before we can use antibody testing to track the spread of COVID-19 and identify 'hot spots' of the disease."

Source:

Massachusetts General Hospital

Journal reference:

Iyer, A. S., et al. (2020) Persistence and decay of human antibody responses to the receptor binding domain of SARS-CoV-2 spike protein in COVID-19 patients. Science Immunology. doi.org/10.1126/sciimmunol.abe0367.
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Re: How long is antibody duration in Covid 19 ? / Antibodies

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Long-lasting antibodies detected in blood and saliva of COVID-19 patients

10/9/20


https://www.news-medical.net/news/20201 ... ients.aspx

Two separate studies have documented the persistence of antibodies that target SARS-CoV-2 in hundreds of patients with COVID-19 at least 3 months after symptom onset.

Both studies point to the IgG class of antibodies as the longest-lasting antibodies detectable in the blood and saliva of patients during this timeframe, suggesting that SARS-CoV-2-specific IgG antibodies may serve as promising targets to detect and evaluate immune responses against the virus.

That these antibodies could be detected at similar levels in both blood and saliva suggests that saliva could be used as an alternative biofluid for antibody testing.

In the first study, Anita Iyer and colleagues measured antibody responses in the blood of 343 patients with COVID-19 for up to 122 days after symptom onset - and compared these responses to those of 1,548 control individuals sampled before the pandemic.

The researchers focused only on antibodies specific to the SARS-CoV-2 spike protein's receptor binding domain. To provide a baseline, the researchers estimated sensitivities of IgG, IgA, and IgM antibody types at 95%, 90%, and 81%, respectively, for detecting infected individuals between 15 to 28 weeks after symptom onset.

Among these antibodies, spike protein-specific IgM and IgA were short-lived, dropping beneath detection levels at around 49 and 71 days, respectively, after the appearance of symptoms. In contrast, spike protein-targeted IgG responses decayed slowly over a period of 90 days, with only 3 individuals losing them within this timeframe.

Levels of spike protein-specific IgG strongly correlated with levels of neutralizing antibodies in the patients. The researchers also did not observe cross-reactivity of any SARS-CoV-2-targeting antibodies with other "common cold" coronaviruses.

Similar to Iyer et al., Baweleta Isho and colleagues found that while IgA and IgM antibodies targeting the spike protein's receptor binding domain rapidly decayed, IgG antibodies remained relatively stable for up to 105 days after symptom onset in 402 patients with COVID-19.

The researchers detected spike protein-specific antibodies in the saliva, as well as the blood, of these patients. They charted the patients' antibody responses from 3 to 115 days after symptom onset, and compared their profiles with 339 pre-pandemic controls. Patients with COVID-19 showed peak IgG levels at 16 to 30 days after the appearance of symptoms.

Levels of all spike protein-specific IgG, IgM, and IgA antibodies in the blood positively correlated with levels observed in matched saliva samples.

The authors stated,

Given that the virus can also be measured in saliva by PCR, using saliva as a biofluid for both virus and antibody measurements may have some diagnostic value."

Source:


American Association for the Advancement of Science

Journal reference:

Iyer, A. S., et al. (2020) Persistence and decay of human antibody responses to the receptor binding domain of SARS-CoV-2 spike protein in COVID-19 patients. Science Immunology. doi.org/10.1126/sciimmunol.abe0367.
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Re: How long is antibody duration in Covid 19 ? / Antibodies

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New study reports on extremely potent human monoclonal antibodies for SARS-CoV-2

10/11/20


https://www.news-medical.net/news/20201 ... CoV-2.aspx

Researchers have recovered and identified the various types of neutralizing antibodies for SARS-CoV-2 from convalescent COVID-19 patients. Of these, they identified three that are extremely potent and could be used to develop treatment therapies.

As the COVID-19 pandemic sweeps across the globe, there have been urgent efforts to contain its spread. In the absence of any drugs or vaccines against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the strategy has been to implement social distancing and quarantine.

However, these strategies have not been efficiently implemented in all countries, limiting disease prevention. Thus, the need to develop vaccines and therapies to combat the disease has become critical.

It has also been predicted that the disease will continue to spread and there will be further waves until we reach herd immunity, either using a vaccine or naturally. Thus, there is a need to develop treatments for the disease in addition to developing vaccines.

Several types of human monoclonal antibodies (mAbs), which are antibodies produced in the lab to target a specific antigen, are now commercially available for treating a variety of diseases. Given the significant clinical experience in making mAbs, mAbs to target SARS-CoV-2 may be a route to develop therapies quickly.

Several researchers have been isolating human mAbs from COVID-19 patients who have recovered. Many of these have only moderate potency to neutralize the virus. A few grams of the antibodies may be required per person to effectively combat the virus, which will require injecting the antibodies in the bloodstream, rather than intramuscular injections.

Human monoclonal antibodies from recovered patients

A new study published on the preprint server bioRxiv* reports on screening and characterizing mAbs from recovered COVID-19 patients to identify and recover the most potent antibodies against SARS-CoV-2.

The SARS-CoV-2 virus infects humans by attaching itself to the human angiotensin-converting enzyme 2 (ACE2) via the spike protein. The spike protein exists in a metastable conformation before fusion and a stable conformation after fusion to ACE2. The receptor-binding domain (RBD) of an S1 subunit of the spike protein attaches to ACE2.

So, the researchers targeted mAbs specific to the spike protein. To recover these mAbs, the authors collected peripheral blood mononuclear cells (PBMCs) from 14 convalescent patients. They stained the spike protein to identify the spike protein-specific memory B cells (MBCs). They recovered about 4300 different MBCs, which they incubated for two weeks to allow for the production of immunoglobulins.

After that, they screened these antibodies produced for specific binding to the spike protein using ELISA and recovered 1731 mAbs.

The authors tested the ability of these 1731 mAbs to block the binding of the spike protein to Vero E6 cell receptors and to neutralize SARS-CoV-2 using in vitro assays. They found 19.6% of the mAbs blocked spike protein binding with potency ranging from 50% to 100%.

When they tested the ability of these mAbs to protect the Vero E6 from SARS-CoV-2 infection, they found 453 mAbs neutralized the live virus.

Most of the neutralizing mAbs, about 58%, specifically recognized the S1 subunit, about 7% specifically recognized the S2 subunit of the spike protein, and about 35% recognized the spike protein trimeric configuration.

Next, the authors tested how good was the neutralizing potency of the mAbs identified above. They found about 66% had low neutralizing potency, requiring more than 500 ng/mL for achieving IC100, about 24% had medium potency, and about 1.4% were extremely potent, with an IC100 of less than 10 ng/mL.

Extremely potent antibodies

The researchers selected 14 mAbs from their first round of screening to continue investigating. Of these, some were able to bind to the S1 or S2 subunits and others to the spike protein trimeric configuration.

Of the neutralizing mAbs binding to the S1 subunit, 6 mAbs bound to the RBD and were extremely potent for neutralizing the virus.

Antibodies that bound to the spike protein trimeric configuration had lower neutralizing potency compared to those that bound to RBD or the S1 subunit. The antibodies binding only to the S2 subunit showed the lowest neutralizing potency.

“From these data we conclude that in convalescent patients most of the observed neutralization titers are mediated by the antibodies with medium-high neutralizing potency,” write the authors. The extremely potent antibodies and antibodies binding to S2 are too few to have any effect.

Hence, it will be important to understand the types of antibodies produced after vaccination, write the authors, as vaccination may produce different sets of neutralizing antibodies.

Of the 453 mAbs the authors screened, the team found three mAbs that had extremely high neutralization potency against the SARS-CoV-2 strain from Wuhan and the D614 strain.

These antibodies will allow the use of small quantities to be used to achieve therapeutic benefits, reducing the cost of treatment.


Journal reference:

Andreano, E. et al. (2020) Extremely potent human monoclonal antibodies from convalescent Covid-19 patients. bioRvix. https://doi.org/10.1101/2020.10.07.328302
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COVID-19 survivors may have protective antibodies for 4 months

10/11/20


https://www.news-medical.net/news/20201 ... onths.aspx


A new study by researchers at Harvard Medical School and the Massachusetts General Hospital (MGH) aimed to determine how long severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunity in COVID-19 survivors lasts. The researchers found that people who survive severe COVID-19 disease have long-lasting immune responses against SARS-CoV-2.

The study, published in the journal Science Immunology, highlights the body's immune response against COVID-19. Also, it offers hope that people who are infected with the SARS-CoV-2 virus will develop lasting protection against reinfection.

The study

In the study, the researchers focused on the receptor-binding domain (RBD) of the virus "spike" protein, which binds to cells through the angiotensin-converting enzyme 2 (ACE2) receptors, leading to infection.

The immune system generates proteins called antibodies when it senses that pathogens like the SARS-CoV-2 invade the body. Though the body produces an immune response, it is unclear how long these antibody responses last.

To arrive at the study findings, the research team collected blood samples from 343 patients infected with SARS-CoV-2, most of whom had severe cases. These blood samples were obtained up to four months after the symptoms appeared.

The researchers isolated the blood plasma and applied to laboratory plates coated with the RBD of the spike protein. They analyzed how different types of antibodies in the plasma attached to RBD. The study results were compared with blood samples collected from 1,548 people before the pandemic.

The study findings showed that the immunoglobulin G (IgG) levels remained elevated in COVID-19 patients for four months and were tied to the presence of protective neutralizing antibodies, which exhibited a little reduction in activity over time.

Hence, people are very likely to be protected for four months, which shows that key antibody responses to COVID-19 are present, the researchers concluded.

IgG level measurements more accurate

Also, they found that measuring the IgG levels was more accurate in detecting people who had symptoms for at least 14 days.

"These data suggest that RBD-targeted antibodies are excellent markers of previous and recent infection, that differential isotype measurements can help distinguish between recent and older infections, and those IgG responses persist over the first few months after infection and are highly correlated with neutralizing antibodies," the researchers wrote in the paper.

They added that since the standard test for SARS-CoV-2, the Polymerase chain reaction (PCR) nasal swab, loses sensitivity over time, supplementing it with an antibody test in patients who developed symptoms for at least eight days can aid in identifying some positive cases that may be missed.

The team also added that people who were infected with the coronavirus had immunoglobulin A (IgA) and immunoglobulin M (IgM) responses that lasted for short periods decreasing to low levels in about two and a half months after infection. If patients tested positive for these antibodies, they might have been infected with COVID-19 in the past two months.

Being aware of the duration of the body's immune responses against SARS-CoV-2 by testing IgA and IgM levels will help provide more precise data about the spread of the infection.


"There are a lot of infections in the community that we do not pick up through PCR testing during acute infection, and this is especially true in areas where access to testing is limited," Jason Harris, a pediatric infectious disease specialist at MGH, explained.

"Knowing how long antibody responses last is essential before we can use antibody testing to track the spread of COVID-19 and identify 'hot spots' of the disease," he added.

Of the more than 37.39 million cases of COVID-19 globally, more than 25.99 million have already recovered. Currently, numerous vaccines are being trialed to see if they are effective and safe to use by the general public. Having a better understanding of the body's antibody responses to SARS-CoV-2 will also help scientists develop a vaccine that could offer protection against the raging virus.

Sources:

Harvard Medical School. (2020). https://news.harvard.edu/gazette/story/ ... rotection/
COVID-19 Dashboard by the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University (JHU) - https://gisanddata.maps.arcgis.com/apps ... 7b48e9ecf6

Journal reference:

Iyer, A., Jones, F., Nodoushani, A. et al. (2020). Persistence and decay of human antibody responses to the receptor-binding domain of SARS-CoV-2 spike protein in COVID-19 patients. Clinical Immunology. https://immunology.sciencemag.org/content/5/52/eabe0367
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Re: How long is antibody duration in Covid 19 ? / Antibodies

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How long is antibody duration in covid 19 ?

(The antibody duration information is changing , as results from new research are added to the body of knowledge on this topic)

COVID-19 Antibodies Last for at Least Four Months After Recovery

9/2/20

https://www.the-scientist.com/news-opin ... very-67907


In Convalescent Plasma, 3 - 4 Months


COVID-19 antibodies in convalescent plasma donations wane by 3 to 4 months

10/1/20


https://www.healio.com/news/hematology- ... o-4-months
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