2021.7.26, 8.31: news.health/immunity/covid-19/
natural immunity after infection persists even with low antibodies:
summary:
. it is shown that after a covid-19 infection
there is long-lasting immunity
even when the antibody count is low
because covid-19 is slowly developing
thereby giving the memory cells time to react
by growing more antibodies when needed.
. the CDC recommends even those who have been infected
should get the vaccine; apparently because,
the recently vaccinated with their higher antibodies,
will be quicker at stopping the spread of the virus
than people who have survived an infection and then
slowly make more antibodies when reinfected.
. the politics of this question are based on
a dispute over the likelihood of vaccine injury.
Nature 2021
https://pubmed.ncbi.nlm.nih.gov/34030176/
SARS-CoV-2 infection induces long-lived bone marrow plasma cells in humans
Jackson S. Turner, et al
full text of the pre-print:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7781328/
"Long-lived bone marrow plasma cells (BMPCs)
are a persistent and essential source of
protective antibodies.
1–7
Individuals who have recovered from COVID-19
have a substantially lower risk of reinfection.
8–10
Nonetheless, it has been reported that
levels of anti-SARS-CoV-2 serum antibodies
decrease rapidly in the first few months after infection,
raising concerns that
long-lived BMPCs may not be generated
and humoral immunity against SARS-CoV-2
may be short-lived.
11–13
Consistently, circulating resting memory B cells
directed against SARS-CoV-2 S
were detected in the convalescent individuals.
Overall, our results indicate that
mild infection with SARS-CoV-2 induces
robust antigen-specific, long-lived
humoral immune memory in humans."
. that study was referenced by
immunology professor Ali Ellebedy
who commented:
“Last fall, there were reports that antibodies wane quickly
after infection with the virus that causes COVID-19,
and mainstream media interpreted that to mean
that immunity was not long-lived;
But that’s a misinterpretation of the data.
It’s normal for antibody levels to
go down after acute infection, [...]
Here, [in the above study] we found
antibody-producing cells in people
11 months after first symptoms.
These cells will live and produce antibodies
for the rest of people’s lives.
That’s strong evidence for long-lasting immunity.”
[Washington U School of Med Tamara Bhandari May 24, 2021]
https://medicine.wustl.edu/news/good-news-mild-covid-19-induces-lasting-antibody-protection/
. covid-19 is slowly developing,
thereby giving the memory cells time to react
by growing more antibodies when needed.
Science February 5, 2021:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7919858/
Immunological memory to SARS-CoV-2 assessed for
up to 8 months after infection.
Jennifer M. Dan, et al.
"While sterilizing immunity against viruses
can only be accomplished by high-titer neutralizing antibodies,
successful protection against clinical disease or death
can be accomplished by several other immune memory scenarios.
Possible mechanisms of immunological protection
can vary based on the relative kinetics of
the immune memory responses and infection.
For example, clinical hepatitis after a
hepatitis B virus (HBV) infection
is prevented by vaccine-elicited immune memory
even in the absence of circulating antibodies,
because of the relatively slow course of HBV disease
(32, 33).
The relatively slow course of severe COVID-19 in humans
(median 19 days post-symptom onset (PSO) for fatal cases
(34))
suggests that protective immunity against
symptomatic or severe secondary COVID-19
may involve memory compartments such as
circulating memory T cells and memory B cells
(which can take several days to reactivate
and generate recall T cell responses
and/or anamnestic antibody responses)
(19, 21, 31)."
. the CDC recommends even those who have been infected,
should get the vaccine;
but, the authors of one peer-reviewed study shows
the infected rarely suffer from a future infection.
. apparently the CDC's position is that
the recently vaccinated with their higher antibodies,
will be quicker at stopping the spread of the virus
than people who have survived an infection and then
slowly make more antibodies when reinfected.
Lancet. 2021 17-23 April;
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8040523/
SARS-CoV-2 infection rates of antibody-positive compared with
antibody-negative health-care workers in England:
a large, multicentre, prospective cohort study (SIREN)
Victoria Jane Hall, FFPH, et al.
"This study shows that previous infection with SARS-CoV-2
induces effective immunity to future infections
in most individuals."
. there was a similar result by the Cleveland Clinic
but it seems to have failed to pass peer review
perhaps because they bluntly stated that
we should save the precious little vaccine we have
for the world's most vulnerable to severe covid
(who is suppose to pay for that?).
preprint June 19, 2021
https://www.medrxiv.org/content/10.1101/2021.06.01.21258176v3
Necessity of COVID-19 vaccination in previously infected individuals.
Nabin K. Shrestha, et al
"Cumulative incidence of COVID-19 was examined among
52238 employees in an American healthcare system.
COVID-19 did not occur in anyone
over the five months of the study
among 2579 individuals previously infected with COVID-19,
including 1359 who did not take the vaccine.
Individuals who have had SARS-CoV-2 infection
are unlikely to benefit from COVID-19 vaccination,
and vaccines can be safely prioritized to
those who have not been infected before."
Dr. Sanchari Sinha Dutta analyzes that study:
"In order to ensure fair access to vaccines
throughout the world,
the COVID-19 vaccines Global Access
(COVAX) initiative was launched.
In many countries,
especially those with low socioeconomic status,
there is a serious shortage of vaccines.
Thus, in order to get the maximum vaccine benefits,
the most vulnerable population should be
prioritized for the vaccination."
a rebuttal of that study:
"The study demonstrated that previous infection
protects against COVID-19,
but not the effect of vaccination
in previously infected individuals."
"The first caveat in the study is that
the authors defined SARS-CoV-2 infection as a
positive RT-PCR test result during routine testing at the clinic.
However, the clinic didn’t routinely test employees without symptoms.
Therefore, people with mild or no symptoms
might have been wrongly classified as previously uninfected
or gone undetected during the study.
Given the small number of infections observed in most of the groups,
a few misclassified or undetected infections
might change the conclusions of the study.
. Furthermore, people without symptoms can still
transmit the virus to others,
as Health Feedback explained in this review.
Posts claiming that vaccination in
previously infected individuals
is useless disregard the potential benefits of vaccines
in preventing viral transmission within the community."
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