SvennoJ said:
haxxiy said:
Here's a study about it from 2014 about this and coronaviruses that should clarify a few things: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4125530/
A noteworthy paragraph: "Follow-up studies from patients who recovered from SARS suggest that the SARS-CoV-specific antibody response is short lived. In these patients, SARS-CoV-specific IgM and IgA response lasted less than 6 months, while virus-specific IgG titer peaked four-month post-infection and markedly declined after 1 year. Despite the lack of virus-specific memory B cell response, SARS-CoV-specific memory T cells persist in SARS-recovered patients for up to 6 years post-infection."
Of course, if your doctor is telling you you should be careful, then you should be careful. I'm evidently not trying to be dismissive about it. Even seemingly innocuous infections can have consequences (adenoviruses can be particularly insidious, for instance) and more severe ones will almost always have them, at least for some time, even if you are immunologically protected against that specific infection.
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They compare Sars-Cov-2 antibody duration with SARS/Mers in this study
https://www.nature.com/articles/s41591-020-0965-6
The strength and duration of immunity after infection are key issues for ‘shield immunity’18 and for informing decisions on how and when to ease physical distancing restrictions19,20. Previous studies have shown that circulating antibodies against SARS-CoV or MERS-CoV last for at least 1 year21,22. Sustained IgG levels were maintained for more than 2 years after SARS-CoV infection23,24. Antibody responses in individuals with laboratory-confirmed MERS-CoV infection lasted for at least 34 months after the outbreak25.
Recently, several studies characterizing adaptive immune responses to SARS-CoV-2 infection have reported that most COVID-19 convalescent individuals have detectable neutralizing antibodies, which correlate with the numbers of virus-specific T cells26,27,28,29. In this study, we observed that IgG levels and neutralizing antibodies in a high proportion of individuals who recovered from SARS-CoV-2 infection start to decrease within 2–3 months after infection. In another analysis of the dynamics of neutralizing antibody titers in eight convalescent patients with COVID-19, four patients showed decreased neutralizing antibodies approximately 6–7 weeks after illness onset30.
One mathematical model also suggests a short duration of immunity after SARS-CoV-2 infection31. Together, these data might indicate the risks of using COVID-19 ‘immunity passports’ and support the prolongation of public health interventions, including social distancing, hygiene, isolation of high-risk groups and widespread testing. Additional longitudinal serological studies profiling more symptomatic and asymptomatic individuals are urgently needed to determine the duration of antibody-mediated immunity. In addition, low levels of anti-viral IgG in asymptomatic patients, who might be more likely to become seronegative, further support the need for timely serosurvey to study the true infection rate.
Preliminary studies suggest that immunity from SARS-COV-2 is shorter and less effective than for SARS and MERS. It's still early days though, it has only been 3 months since the patients in this study got infected. Asymptomatic patients lose the immunity IgG anti bodies a lot faster and I imagine they also produced fewer T-cells against Sars-Cov-2.
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MERS is often held by medical studies as having an infamously poor antibody response that isn't always readily detectable. To a lesser extent, that was also the case with SARS:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5512479/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4880093/
The research that the article mentions does refer to detection after 34 months, albeit at reduced levels and taking only select cases (a grand total of seven people) that had detectable antibodies to begin with, to develop a follow-up study:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5038413/
Why they have decided to present it as some sort of consensus or ordinary feature of MERS? No idea. You are free to draw your own conclusions.
Mind you, the same difficulties concerning neutralizing antibody titers and coronaviruses have been noticed all the way back to the 70s:
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/77BBFFC8CDBB77DAEDB4BEBCA3D0F14F/S0022172400022294a.pdf/coronavirus_antibody_titres_in_sera_of_healthy_adults_and_experimentally_infected_volunteers.pdf
Of course, with MERS and others, the negative results were often credited to issues with the methods used instead of automatically being credited to a proper response being inexplicably absent, since empirical evidence showcases even a mild coronavirus disease protect you for at least about a year of the same virus. One would think that is also the case here, considering how novel the disease and all the tools we have are and how much, time and time again, false negatives have been shown to abound relative to SARS-CoV-2 testing.
I understand people want to be careful around this, but some people are acting as if it is the first time a pandemic has happened and nobody knows if the world will end or not.
Edit - I haven't found the paper itself, but I've seen a news article where an immunologist mentions a small study on recently infected people found most of them had memory cells but no (detectable) antibodies. So one wouldn't necessarily follow the other or depend on its prevalence too.
Last edited by haxxiy - on 25 June 2020
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