Hey everybody, it's Dr. Z.
Okay so people have been freaking out with this data
that's come out that antibody responses
to the coronavirus that causes COVID-19 have been shown
in a King's college study out of London
to actually drop quite dramatically over a period
of mere weeks after people have been exposed to the disease.
Now, why does that matter?
Why is that a big deal?
Well, it turns out that we assume that antibodies,
which are little proteins made by B cells
from our immune system are what is conferring resistance
to disease once you've been infected
and what that means is that when you're exposed
to a virus, the immune system learns,
okay, these are the different proteins on the virus
and we can actually make antibodies that bind
to those proteins that then can inactivate the virus
with the help of other cells in the immune system
and the concern if antibodies that are measured
in the blood, don't seem to be very durable.
Oh my gosh, we could be reinfected
even if we've had the disease before
or worse yet a vaccine which functions
by inducing antibody response, won't be very effective
because the antibodies will disappear and we're still,
we can never achieve something called herd immunity,
meaning there's enough immunity in the population
that the virus has nowhere to go
and I've talked about this in other videos
because the antibody response doesn't stick around
and you have these anecdotal reports
of people getting infected again and generalized panic
but what people are missing
and this has come out in more information,
I'm gonna put links in the web post for this video
that you should check out,
especially if you're a big nerd and wanna go deep.
There's a second branch of the immune system that instead
of being comprised of B cells that make antibodies,
they're comprised of things called T cells,
they help with something called cell-mediated immunity.
Now T cells are actually the ones
that are generally knocked out of commission,
helper T cells in HIV,
which is one of the problems with HIV.
So T cell responses can be long lasting
and they're particularly good with viruses it appears
and the idea with T cells
that we haven't really been measuring them that much.
There's some studies that have done this
and some pre-prints, again, check out the links
but the response to this SARS 2 coronavirus may well be
really led by a T cell response
and there are some pre-print data that Eric Topol shared
with an article in The Atlantic that I'm gonna link to
that actually looked at families in Europe
that had been exposed to coronavirus
and a lot of them had antibodies
but then a lot of the family members
that were clearly exposed had even had symptoms,
tested negative for any antibodies at all.
So did they ever have the disease, what's going on?
But when they tested them for T cells
that would have been made
in response to a coronavirus exposure,
they were more likely positive
and remember they had mild symptoms or no symptoms
so it might've been that they mounted a T cell response
that led to some degree of immunity
and actually did quite well.
So maybe we're just not measuring everything
that should be measured
and maybe actually we're missing a lot of positive cases
of people who've been exposed in the past
that have no antibodies
but actually have mounted a T cell response.
Now there's actually speculation.
It's a little bit beyond speculation now
that exposure to other coronaviruses,
common cold coronaviruses or in the case of the OG SARS,
the original SARS CoV1 and MERS,
which is also coronavirus, human coronavirus.
Those folks have shown durable,
longer lasting T cell responses,
even if they had rapidly declining antibody responses
and that's encouraging because
it means there may be a longer lasting immunity,
maybe that subsequent reinfections,
if they occur may be less severe as is the case,
it's felt to be the case with the coronaviruses
that cause the common cold.
It also might explain some interesting things.
Now this is speculation but others have speculated this.
Why do children get less severe disease
or no disease or asymptomatic disease?
And the thought is that well
because they're festering little cesspools of coronavirus
in general, the common cold
and they may mount a very early T cell response
that actually gives them cross-protection
against coronaviruses that share some similarities
like the SARS 2 coronavirus that causes COVID-19.
In which case that T cell response is really interesting.
So what does this say?
Let's go through it systematically.
What does this say for vaccine production?
Well, this is interesting
because the vaccines are really focused
on antibody production
and triggering neutralizing antibodies
that bind to a part of the capsule of the coronavirus
that would then neutralize it
and if antibodies wane really fast,
well, that could be bad news or it could say,
well, that's true, the overall antibody count
that you measure in the blood has been dropping
but there's a memory in the immune system
that is primed by the original exposure
and there are these things called memory B cells
that actually, the antibodies can drop
but you have these memory B cells
that then can mount a very quick memory-based response to,
and I'm simplifying this a lot response
to the virus when it reappears.
So all hope is not lost if antibodies wane quickly.
The second thing is there's always the possibility
of creating T cell response vaccines.
So an interesting side note and most vaccines don't do this,
they don't create a T cell response
unless you're using an actual organism,
it's like a live attenuated organism
that then can promote the immune system
to respond with T cells
but BCG vaccination that was given historically
for tuberculosis uses bovine cow,
a mycobacterium that's related to human TB but different
and that is probably the only vaccine that works primarily
by inducing a T cell response.
Now what's interesting is it doesn't actually work that well
for tuberculosis but there's data that suggests
that it actually confers some cross-protection
against other viruses,
remember tuberculosis is a mycobacterium,
it's not a virus.
Maybe by producing this robust T cell response,
it actually has cross-protection,
including against the SARS 2 coronavirus
that cause COVID-19.
So this is really interesting
and what it really highlights is when you read a headline
that's doom and gloom,
oh, study shows antibody protection may wane,
meaning herd immunity is doomed,
meaning vaccines are not gonna work.
Think twice, the human immune system is very complex
and it has multiple components
and there's more to this than we think.
The other interesting thing is I've done a piece
on why herd immunity thresholds may actually be lower
because there's a lot of innate resistance
to this coronavirus in the population, it seems.
Again, this is all early thinking
and the science is constantly evolving.
Why would that be?
Cross reaction to other coronaviruses,
durable T cell immunity and could it be that
that T cell immunity actually is a big part
of why some people seem to get knocked out by this thing
and have this huge new immune response
and others just blow it off like it was nothing
and so once we start to understand that,
we can actually come up with strategies that will work.
Now, the worst case scenario is
it is an antibody predominant thing
and the waning antibodies mean any vaccine is gonna have
to be reboosted every year or so.
Well, you know what? We're used to that with influenza.
So if that's the worst case, I'd still take that.
Now there's still a lot of work to be done on vaccination
and it might be that we get
to a lower threshold herd immunity before that,
that shouldn't be our goal because a lot of people would die
if we just let the thing rip through,
which means, like I always say,
I don't care about what your politics are.
I don't care about what you believe, just wear a mask
if you can't social distance,
social distance when you can,
wash your hands and we'll get through this all a lot faster.
So I hope this was helpful.
Please check out the links in the web post that I'll link to
from anywhere I post this thing.
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All right guys, I love you.
I do, stay safe and we out, peace.