There’s been a lot of panic with stories of people getting COVID-19 twice and rapidly plummeting antibody levels. But there may be a real bright spot here.
Here’s a good summary article in the Atlantic. Here’s a Science piece on T-cell mediated immunity. Here’s a pre-print on antibody-vs-T-cell response within families exposed to SARS-CoV2. Here’s a reference on T-cell inducing vaccines and BCG.
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 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 causes 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. This is also an audio podcast, which you can check out. So please subscribe and review on our podcast platforms. People who wanna support the show can do it on YouTube by subscribing there, on Facebook by subscribing there or directly PayPal us if you really care about what we do and wanna support all of this gear and team that we have. All right guys, I love you. I do, stay safe and we out, peace.