What level of antibodies for covid 19 is good - Background To accurately interpret COVID-19 seroprevalence surveys, knowledge of serum-IgG responses to SARS-CoV-2 with a better understanding of patients who do not seroconvert, is imperative. This study aimed to describe serum-IgG responses to SARS-CoV-2 in a cohort of patients with both severe and mild COVID-19, including extended studies of patients who remained seronegative more than 90 ...

 
Of the 175 patients, 165 (94%) had significantly higher levels of COVID-19 antibodies than 13 uninfected controls in the convalescent phase of infection. Antibody levels were medium-low in 29 patients (17%), medium-high in 69 patients (39%), and high in 25 patients (14%). Age, sex, inflammatory response. Sample cover letter for i 751

Oct 20, 2021 · They've confirmed that "antibody levels correlate with pseudoviral and live virus neutralization, and the curves are threshold linear." Several studies have shown that neutralising antibody level is a good biomarker for the correlate of protection against SARS-CoV-2 infection.1–3 However, results from these studies are presented using assays that have not been calibrated using a common reference standard, making it difficult to define the exact level of neutralising antibodies required for protection and to compare with ...Ellebedy’s team tracked antibody production in 77 people who had recovered from mostly mild cases of COVID-19. As expected, SARS-CoV-2 antibodies plummeted in the four months after infection ...Among subjects with previous history of COVID-19 infection the levels of spike protein antibody remained >250 AU/ml post second dose administration. The spike protein antibody level reached peak at 3–4 th week after the second dose administration. We followed up these subsequently at two to three weeks intervals.Oct 20, 2021 · They've confirmed that "antibody levels correlate with pseudoviral and live virus neutralization, and the curves are threshold linear." NIAID. After being infected with SARS-CoV-2, the virus that causes COVID-19, most people develop antibodies against the virus. Antibodies are proteins produced by the immune system that can help fight off the virus if it’s encountered again. However, the relationship between these antibodies and SARS-CoV-2 reinfection is still unclear.It’s these cells that make truly long term immunity possible. A study published in February in Science assessed the proliferation of antibodies as well as T and B cells in 188 people who had had covid-19. 7 Although antibody titres fell, memory T and B cells were present up to eight months after infection.Vaccine efficacy of 80% against primary symptomatic COVID-19 was achieved with an IgG level of 40,923 arbitrary units (AU)/mL for anti-spike and 63,383 Au/mL for anti-RBD. For pseudovirus and live ...Major advances have been made in understanding the dynamics of humoral immunity briefly after the acute coronavirus disease 2019 (COVID-19). However, knowledge concerning long-term kinetics of antibody responses in convalescent patients is limited. During a one-year period post symptom onset, we longitudinally collected 162 samples from 76 patients and quantified IgM and IgG antibodies ...Who should get an COVID-19 antibody test? Much is still unknown about antibody levels and how they correlate to immunity, so there’s limited clinical usefulness to these tests. As the newly published data makes a correlation with higher antibody levels and protection from infection and reinfection, it’s understandable that you may want to ... The SARS-CoV-2 Spike IgG test shows the level of COVID-19 antibodies you had in your blood when you gave the blood sample. Usually your antibody levels will go up after getting a vaccine or having an infection. Having more antibodies means your body can fight infection better than having fewer antibodies. A previous study found that on average ...Dec 20, 2022 · Researchers are trying to find out how much protection antibodies provide against the COVID-19 virus, what the level of protection is and how long immunity may last. Until there is more information, even if your test results show that you have COVID-19 antibodies, keep taking steps to avoid the risk of spreading the virus. Several studies have shown that neutralising antibody level is a good biomarker for the correlate of protection against SARS-CoV-2 infection.1–3 However, results from these studies are presented using assays that have not been calibrated using a common reference standard, making it difficult to define the exact level of neutralising antibodies required for protection and to compare with ...Things could get even thornier. As is the case with any vaccine, the success of a COVID-19 shot hinges on a multitude of factors—including the strength of the immune system it’s bolstering ...Things could get even thornier. As is the case with any vaccine, the success of a COVID-19 shot hinges on a multitude of factors—including the strength of the immune system it’s bolstering ...08/03/2021 Antibodies are important for a vaccination to work, but scientists don't yet know what level they must reach. The new delta variant poses another problem. Coronavirus vaccinations... A relationship between neutralization level after SARS-CoV-2 vaccination and protection against COVID-19 has been demonstrated by several studies. 4 As such, the height of the humoral response after vaccination, which correlates with neutralizing antibody titers, 5 might be clinically relevant.The results, published in the peer-reviewed journal Clinical Infectious Diseases, echo and expand on the preliminary findings reported in this press release of a heterogenous response among people with immunocompromising conditions to COVID-19 vaccination. Specifically, 79.8% of those with HIV, 79.1% of those with autoimmune conditions, and 78. ...There is a strong debate concerning the nature, stability, and durability of antibody responses over time in COVID-19 patients, with several studies reporting stable antibody persistent immunity and others showing rapidly waning antibody immunity, or late appearance with low antibody levels, and/or complete lack of long-lasting antibodies (15 ...When your physician orders antibody testing, often referred to as serology testing, they are looking for the presence of antibodies (qualitative testing) or the level of antibodies (quantitative testing) you have against a specific target, such as a virus.A total of 4290 samples from 393 convalescent COVID-19 and 916 COVID-19 negative individuals were analyzed. In convalescent individuals, SARS-CoV-2 antibodies followed a triphasic kinetic model with half-lives at month (M) 11–13 of 283 days (95% CI 231–349) for anti-N and 725 days (95% CI 623–921) for anti-RBD IgG, which stabilized at a median of 1.54 log BAU/mL (95% CI 1.42–1.67).Major advances have been made in understanding the dynamics of humoral immunity briefly after the acute coronavirus disease 2019 (COVID-19). However, knowledge concerning long-term kinetics of antibody responses in convalescent patients is limited. During a one-year period post symptom onset, we longitudinally collected 162 samples from 76 patients and quantified IgM and IgG antibodies ...The Red Cross told us it continued to test whole blood donations for COVID-19 antibodies until June 14, 2021, and was able to use those with high levels of antibodies as convalescent plasma.Background To accurately interpret COVID-19 seroprevalence surveys, knowledge of serum-IgG responses to SARS-CoV-2 with a better understanding of patients who do not seroconvert, is imperative. This study aimed to describe serum-IgG responses to SARS-CoV-2 in a cohort of patients with both severe and mild COVID-19, including extended studies of patients who remained seronegative more than 90 ...That is, the level of neutralizing antibodies required to protect against 50% of infection is one-fifth of the mean neutralizing antibody titer found in convalescent serum. Again, when adjusted to ...This news story has been updated to reflect the publication of the study, previously available on BioRxiv, in a peer-reviewed journal. Hope for a future without fear of COVID-19 comes down to circulating antibodies and memory B cells. Unlike circulating antibodies, which peak soon after vaccination or infection only to fade a few months later, […]Results. Our data showed good alignment up to 1000 BAU/mL, then began to disperse, exhibiting some discrepancies. Moreover, correlations among methods varied with Cohen’s Kappa ranging from 0.580 to 1.00, with the lowest agreement values for kits using different target antigens or different antibody isotypes, making it clear that the laboratory report should include this information.Covid-19 vaccines offer the potential for protection against severe infection but relatively little is known regarding the profile of the antibody response following first or second vaccination.A relationship between neutralization level after SARS-CoV-2 vaccination and protection against COVID-19 has been demonstrated by several studies. 4 As such, the height of the humoral response after vaccination, which correlates with neutralizing antibody titers, 5 might be clinically relevant.There are some major problems with relying on community infection to create herd immunity to the virus that causes COVID-19: Reinfection. It's estimated that getting COVID-19 results in a low risk of another infection with a similar variant for at least six months. However, even if you have antibodies, you could get COVID-19 again.The levels have not yet been defined for the coronavirus, however. So doctors approximate, with measured levels ranging from less than a hundred to several thousand antibodies. "If I am in the upper third or in the upper half, I probably have good immune protection. But I can't give you the exact threshold values yet," Watzl says.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.advertisement. FULL STORY. In a study of patients with COVID-19 being treated in intensive care units, people who mounted only a low antibody response against the SARS-CoV-2 virus faced a higher ...The results, published in the peer-reviewed journal Clinical Infectious Diseases, echo and expand on the preliminary findings reported in this press release of a heterogenous response among people with immunocompromising conditions to COVID-19 vaccination. Specifically, 79.8% of those with HIV, 79.1% of those with autoimmune conditions, and 78. ...Shots - Health News New Blood Tests Should Show How Long A COVID-19 Vaccine Will Protect You The results show that antibody levels can be predictive of immunity, which should help develop and...Antibodies responding to SARS-CoV-2 particles (illustration). Researchers are investigating heightened immune responses in people who are vaccinated after recovering from COVID-19.Of the 175 patients, 165 (94%) had significantly higher levels of COVID-19 antibodies than 13 uninfected controls in the convalescent phase of infection. Antibody levels were medium-low in 29 patients (17%), medium-high in 69 patients (39%), and high in 25 patients (14%). Age, sex, inflammatory responseThings could get even thornier. As is the case with any vaccine, the success of a COVID-19 shot hinges on a multitude of factors—including the strength of the immune system it’s bolstering ...A relationship between neutralization level after SARS-CoV-2 vaccination and protection against COVID-19 has been demonstrated by several studies. 4 As such, the height of the humoral response after vaccination, which correlates with neutralizing antibody titers, 5 might be clinically relevant.Objectives To quantify SARS-CoV2 IgG antibody titers over time and assess the longevity of the immune response in a multi-ethnic population setting. Setting This prospective study was conducted in a tertiary hospital in Abu Dhabi city, UAE, among COVID-19 confirmed patients. The virus-specific IgG were measured quantitatively in serum samples from the patients during three visits over a period ...That is, the level of neutralizing antibodies required to protect against 50% of infection is one-fifth of the mean neutralizing antibody titer found in convalescent serum. Again, when adjusted to ...Why it's done Antibody testing for COVID-19 may be done if: You had symptoms of COVID-19 in the past but weren't tested. You had a serious reaction to the first shot of a COVID-19 vaccine. You've had a COVID-19 infection in the past and want to donate plasma.Consequently, spike became the prime target for COVID-19 drug and vaccine developers. The three vaccines authorized by the Food and Drug Administration (FDA) for emergency use in the U.S. — made by Pfizer/BioNTech, Moderna and Johnson & Johnson — all target spike. And potent anti-spike antibodies were selected for development into antibody ...SARS-CoV-2-specific serum-IgG antibodies in severe and mild COVID-19. Forty-seven patients provided a total of 156 serum samples (mean 3.3 per patient, range 1–7), 5–117 days PSO. Of the 47 patients, 15/47 (32%) had severe and 32/47 (68%) had mild COVID-19 (Table 1). The patients with severe symptoms were older (mean age 58) and all male ...Results were published on November 23, 2021, in Science. Antibodies were measured in blood samples taken 4 weeks after the first and second vaccine doses. Levels of both binding and neutralizing antibodies were lower in people who later developed COVID-19 than in people who didn’t get sick. The protection conferred by the vaccine increased as ...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.The results indicate that the BNT162b2 vaccine is highly immunogenic and elicits more antibodies than in response to natural infection. Real-world studies in countries like Qatar where the ...Allergy (European Journal of Allergy and Immunology), Gattinger, P. et al., July 30, 2020, doi: 10.1111/all.14523, “Antibodies in serum of convalescent patients following mild COVID‐19 do not ...In conclusion, we found a significant ongoing increase in avidity maturation after Covid-19, whilst the serum levels of spike- and nucleocapsid- antibodies were declining. Avidity, or the absence of avidity maturation, might be of clinical value to indicate long-term immunity and risk of re-infection. Go to: 6.A test for viral infection detects the virus or a component of the virus and tells you if you have a current COVID-19 infection. This is done using a swab from your nose or throat, or a saliva sample. An antibody (serology) test tells if you have antibodies to the SARS-CoV-2 virus. These antibodies may have developed in response to a previous ...Covid-19 vaccines offer the potential for protection against severe infection but relatively little is known regarding the profile of the antibody response following first or second vaccination.There are some major problems with relying on community infection to create herd immunity to the virus that causes COVID-19: Reinfection. It's estimated that getting COVID-19 results in a low risk of another infection with a similar variant for at least six months. However, even if you have antibodies, you could get COVID-19 again.Major advances have been made in understanding the dynamics of humoral immunity briefly after the acute coronavirus disease 2019 (COVID-19). However, knowledge concerning long-term kinetics of antibody responses in convalescent patients is limited. During a one-year period post symptom onset, we longitudinally collected 162 samples from 76 patients and quantified IgM and IgG antibodies ...The levels have not yet been defined for the coronavirus, however. So doctors approximate, with measured levels ranging from less than a hundred to several thousand antibodies. "If I am in the upper third or in the upper half, I probably have good immune protection. But I can't give you the exact threshold values yet," Watzl says.Early in the pandemic, experts believed that antibodies and natural immunity to COVID-19 lasted for up to 3 months before diminishing. Later evidence suggested that natural immunity could last up ...‘For example, my IgG Covid-19 antibody result after two jabs is 11,728 AU/mL. That’s a good result and shows I have developed antibodies after my vaccines. Not everyone does. However, it’s not the winning score at the LML offices ­ – a colleague was very quick to let me know of his score of 30,238 AU/mL.The results, published in the peer-reviewed journal Clinical Infectious Diseases, echo and expand on the preliminary findings reported in this press release of a heterogenous response among people with immunocompromising conditions to COVID-19 vaccination. Specifically, 79.8% of those with HIV, 79.1% of those with autoimmune conditions, and 78. ...Ellebedy’s team tracked antibody production in 77 people who had recovered from mostly mild cases of COVID-19. As expected, SARS-CoV-2 antibodies plummeted in the four months after infection ...The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease 2019 (COVID-19). Molecular-based testing is used to diagnose COVID-19, and serologic testing of antibodies specific to SARS-CoV-2 is used to detect past infection. While most serologic assays are qualitative, a quantitative serologic ...There are three categories of testing, if I would want to simplify them. The first one is to identify whether the actual COVID virus genetic material exists, and that's called a NAAT test, N-A-A-T. And it's the PCR testing where you would have a nasal pharyngeal swab or a pharyngeal swab taken.It’s these cells that make truly long term immunity possible. A study published in February in Science assessed the proliferation of antibodies as well as T and B cells in 188 people who had had covid-19. 7 Although antibody titres fell, memory T and B cells were present up to eight months after infection.There are some major problems with relying on community infection to create herd immunity to the virus that causes COVID-19: Reinfection. It's estimated that getting COVID-19 results in a low risk of another infection with a similar variant for at least six months. However, even if you have antibodies, you could get COVID-19 again.Why it's done Antibody testing for COVID-19 may be done if: You had symptoms of COVID-19 in the past but weren't tested. You had a serious reaction to the first shot of a COVID-19 vaccine. You've had a COVID-19 infection in the past and want to donate plasma.The levels have not yet been defined for the coronavirus, however. So doctors approximate, with measured levels ranging from less than a hundred to several thousand antibodies. "If I am in the upper third or in the upper half, I probably have good immune protection. But I can't give you the exact threshold values yet," Watzl says.Repeated doses of mRNA vaccines for COVID-19 result in increased proportions of anti-spike antibodies of the IgG4 subclass, which are known to neutralize well and to form mixed immune complexes with IgG1 but, in a pure form, might be less effective than IgG1 or IgG3 antibodies in facilitating opsonization by phagocytes, complement fixation, and ...The estimated in vivo concentration of antibody required for 50% protection from COVID-19 is much higher than the level of antibody required to neutralize virus in vitro (~100-fold), suggesting ...Dec 20, 2022 · Researchers are trying to find out how much protection antibodies provide against the COVID-19 virus, what the level of protection is and how long immunity may last. Until there is more information, even if your test results show that you have COVID-19 antibodies, keep taking steps to avoid the risk of spreading the virus. It’s these cells that make truly long term immunity possible. A study published in February in Science assessed the proliferation of antibodies as well as T and B cells in 188 people who had had covid-19. 7 Although antibody titres fell, memory T and B cells were present up to eight months after infection.Antibodies, after all, are the immunological foot soldiers that ambush troublesome pathogenic invaders before they wreak too much havoc in the body. It stands to reason that if your coronavirus ...Major advances have been made in understanding the dynamics of humoral immunity briefly after the acute coronavirus disease 2019 (COVID-19). However, knowledge concerning long-term kinetics of antibody responses in convalescent patients is limited. During a one-year period post symptom onset, we longitudinally collected 162 samples from 76 patients and quantified IgM and IgG antibodies ...Results were published on November 23, 2021, in Science. Antibodies were measured in blood samples taken 4 weeks after the first and second vaccine doses. Levels of both binding and neutralizing antibodies were lower in people who later developed COVID-19 than in people who didn’t get sick. The protection conferred by the vaccine increased as ...The newly authorized antibody test, called COVID-SeroKlir, identifies and measures precise levels of antibodies that are present in a person after Covid-19 recovery. CNN values your feedback 1.Objectives To quantify SARS-CoV2 IgG antibody titers over time and assess the longevity of the immune response in a multi-ethnic population setting. Setting This prospective study was conducted in a tertiary hospital in Abu Dhabi city, UAE, among COVID-19 confirmed patients. The virus-specific IgG were measured quantitatively in serum samples from the patients during three visits over a period ...advertisement. FULL STORY. In a study of patients with COVID-19 being treated in intensive care units, people who mounted only a low antibody response against the SARS-CoV-2 virus faced a higher ...Repeated doses of mRNA vaccines for COVID-19 result in increased proportions of anti-spike antibodies of the IgG4 subclass, which are known to neutralize well and to form mixed immune complexes with IgG1 but, in a pure form, might be less effective than IgG1 or IgG3 antibodies in facilitating opsonization by phagocytes, complement fixation, and ...In conclusion, we found a significant ongoing increase in avidity maturation after Covid-19, whilst the serum levels of spike- and nucleocapsid- antibodies were declining. Avidity, or the absence of avidity maturation, might be of clinical value to indicate long-term immunity and risk of re-infection. Go to: 6.Dec 20, 2022 · Researchers are trying to find out how much protection antibodies provide against the COVID-19 virus, what the level of protection is and how long immunity may last. Until there is more information, even if your test results show that you have COVID-19 antibodies, keep taking steps to avoid the risk of spreading the virus. Antibodies responding to SARS-CoV-2 particles (illustration). Researchers are investigating heightened immune responses in people who are vaccinated after recovering from COVID-19.Of the 175 patients, 165 (94%) had significantly higher levels of COVID-19 antibodies than 13 uninfected controls in the convalescent phase of infection. Antibody levels were medium-low in 29 patients (17%), medium-high in 69 patients (39%), and high in 25 patients (14%). Age, sex, inflammatory responseThe Red Cross told us it continued to test whole blood donations for COVID-19 antibodies until June 14, 2021, and was able to use those with high levels of antibodies as convalescent plasma.Between June 15 and Oct. 31, the Red Cross tested more than 1.8 million donations in 44 states. Of those donations tested, approximately 2.8% were positive for COVID-19 antibodies. According to Dr. Pampee Young, Chief Medical Officer of the American Red Cross, “With only 2% of the U.S. population testing positive for COVID-19 antibodies ...He's the bearer of good news — and tons of COVID-19 antibodies. ... My antibodies were so high I was a rare Level 4 donor. My antibody titers were over 10,000. They said it wasn’t super common ...Objectives To quantify SARS-CoV2 IgG antibody titers over time and assess the longevity of the immune response in a multi-ethnic population setting. Setting This prospective study was conducted in a tertiary hospital in Abu Dhabi city, UAE, among COVID-19 confirmed patients. The virus-specific IgG were measured quantitatively in serum samples from the patients during three visits over a period ...A booster of the Moderna COVID-19 vaccine increased levels of neutralizing antibodies against all variants of concern in a primate study. The findings suggest that COVID-19 boosters not only lengthen immunity but help broaden and strengthen the immune response. Levels of antibodies that can neutralize SARS-CoV-2 begin to decline weeks after ...

Several studies have shown that neutralising antibody level is a good biomarker for the correlate of protection against SARS-CoV-2 infection.1–3 However, results from these studies are presented using assays that have not been calibrated using a common reference standard, making it difficult to define the exact level of neutralising antibodies required for protection and to compare with .... Sephora j

what level of antibodies for covid 19 is good

Ellebedy’s team tracked antibody production in 77 people who had recovered from mostly mild cases of COVID-19. As expected, SARS-CoV-2 antibodies plummeted in the four months after infection ...In one cluster of COVID-19 patients from China, most people produced high levels of neutralizing antibodies that prevent the virus from infecting new cells, according to a preliminary report ...In the case of COVID, after we’ve been either infected or vaccinated, we produce an antibody to fight the ‘spike protein’ that comes into our bodies with COVID-19. COVID uses the spike ...NIAID. After being infected with SARS-CoV-2, the virus that causes COVID-19, most people develop antibodies against the virus. Antibodies are proteins produced by the immune system that can help fight off the virus if it’s encountered again. However, the relationship between these antibodies and SARS-CoV-2 reinfection is still unclear.The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease 2019 (COVID-19). Molecular-based testing is used to diagnose COVID-19, and serologic testing of antibodies specific to SARS-CoV-2 is used to detect past infection. While most serologic assays are qualitative, a quantitative serologic ...Among subjects with previous history of COVID-19 infection the levels of spike protein antibody remained >250 AU/ml post second dose administration. The spike protein antibody level reached peak at 3–4 th week after the second dose administration. We followed up these subsequently at two to three weeks intervals.For comparison, the scientists also obtained bone marrow from 11 people who had never had COVID-19. As expected, antibody levels in the blood of the COVID-19 participants dropped quickly in the first few months after infection and then mostly leveled off, with some antibodies detectable even 11 months after infection.A correlate of protection (CoP) is urgently needed to expedite development of additional COVID-19 vaccines to meet unprecedented global demand. To assess whether antibody titers may reasonably predict efficacy and serve as the basis of a CoP, we evaluated the relationship between efficacy and in vitro neutralizing and binding antibodies of 7 ...The FDA on Wednesday authorized one of the first Covid-19 tests that measures the amount of neutralizing antibodies produced by the body’s immune system after exposure to the virus — a “new ...Among patients with coronavirus disease (COVID-19), IgM levels increased early after symptom onset for those with mild and severe disease, but IgG levels increased early only in those with severe disease. A similar pattern was observed in a separate serosurveillance cohort. Mild COVID-19 should be investigated separately from severe COVID-19.There are some major problems with relying on community infection to create herd immunity to the virus that causes COVID-19: Reinfection. It's estimated that getting COVID-19 results in a low risk of another infection with a similar variant for at least six months. However, even if you have antibodies, you could get COVID-19 again.“Antibody levels are declining, but something good is happening too: The immune response is evolving. The focus on antibody counts alone actually does a disservice to our understanding of ...Among subjects with previous history of COVID-19 infection the levels of spike protein antibody remained >250 AU/ml post second dose administration. The spike protein antibody level reached peak at 3–4 th week after the second dose administration. We followed up these subsequently at two to three weeks intervals.Robyn Beck / AFP. Experts can't agree on whether to use COVID-19 antibody tests to check whether people need a booster shot. The FDA said on May 19 that antibody tests shouldn't be used to test ...Among patients with coronavirus disease (COVID-19), IgM levels increased early after symptom onset for those with mild and severe disease, but IgG levels increased early only in those with severe disease. A similar pattern was observed in a separate serosurveillance cohort. Mild COVID-19 should be investigated separately from severe COVID-19.The levels have not yet been defined for the coronavirus, however. So doctors approximate, with measured levels ranging from less than a hundred to several thousand antibodies. "If I am in the upper third or in the upper half, I probably have good immune protection. But I can't give you the exact threshold values yet," Watzl says.COVID-19 mRNA vaccine also elicited spike antigen-specific IgA with similar kinetics of induction and time to maximal levels after the 1 st and 2 nd vaccine dose ( Fig 2 ). However, the levels of spike antigen-specific IgA decreased significantly ( p <0.002) faster than IgG levels. Spike-specific IgA decreased to an average of 50% peak levels ..."We know that [naturally infected] people have been fairly well protected against reinfection ... so that gives you an idea that maybe a titer of 1:100 gives quite good, though not perfect,....

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