Is Blood Type a Risk Factor for COVID-19?

[MUSIC PLAYING] Hi, everyone. You're watching Coronavirus in Context. I'm Dr. John Whyte, Chief Medical Officer at WebMD. Thanks for joining me today. We're going to talk about blood type. Have you heard? Maybe your blood type should be considered a risk factor as to whether or not you get COVID. So to help provide some insight, I've asked Dr. Roy Silverstein. He's the Chair of Medicine at the Medical College of Wisconsin. Dr. Silverstein, Thanks for joining me.

Well, thank you for inviting me, John.

You have a great quote that I want to read. You talk about these studies that are looking at blood type. You say "they're a interesting cocktail party conversation, but they may not be ready yet for prime time." Let's talk a little bit about these studies, some have been preprint, that says you have type O, you might do better. And if you have type A, if you go into the hospital with COVID, you might do worse. What's the latest research on blood type?

Well, there is quite a bit of research coming out over the last few weeks and months about blood type and COVID. And it really falls into two categories. Studies that look at whether if you have type O blood you have a lower risk of getting infected, and the other bucket, or other type of studies, suggest that if you have type O blood or that you're less likely to get very, very sick, less likely to need a ventilator in the ICU, for instance, than if you have type A blood. So, two different aspects of the story.

The most recent studies have come out just in the last couple of weeks, in a journal called Blood Advances. And one of them looks at a fairly large population of patients in Denmark. And all of these studies share common methodology, in that they are look-backs. They're not prospective, randomized clinical trials, they're looking at data after the fact, and trying to sort things out to see what might be interesting, what might be real, or what might not be real. Whenever you have studies like that, that are these observational, retrospective studies, it's always good when you have more than one, and it's always more reassuring if more than one come to the same conclusion. And so now we have probably five or six studies on this topic, and almost all of them were coming to the same conclusion. There's one fairly large study from New York, from Columbia, that didn't show any association, but most of the others have, and so they're association studies. The one from Denmark, that just came out, shows that if you look at a population of patients that have COVID, that those who are non-O blood type, particularly type A, seem to have a worse prognosis in the hospital.

And tell our audience, and our clinicians as well, why does that make sense? And if it doesn't, let's call it out and say, it doesn't seem plausible. What's our hypothesis?

So, that's a really important question. Is there biological plausibility for these studies? And I think there probably is, and that's what makes them interesting, and makes a good cocktail party conversation, for both scientists and for the lay public. Because we do know a lot about blood type, we know that blood type is based on the inheritance of genes that encode enzymes that are glycosylates, glycosyltransferases. In other words, they're the enzymes that put sugars on proteins. And we know the proteins function differently depending on the sugars that are on them, so it is plausible that something to do with protein glycosylation could be impacting either the ability of the virus to infect the cell, or the response of the immune system, or the lungs, say, for instance, to the virus.

And so it is possible that antibodies type A could have some kind of cross reactivity with the virus, or with the receptor for the virus, and that could be why the people are less likely to get infected. And in fact, there are actually some in vitro studies, some test tube studies, using the other SARS COVID virus, the SARS-CoV-1, that shows the anti A can partially inhibit the binding of the coronavirus spike protein to its receptor on the lung epithelium. So, there is some biological plausibility there. We do know the blood type has a role in certain malaria type infections. We know that blood type has a role in cholera.

But do most people even know their blood type, do you think?

If you've donated blood, and you're type O, you probably do know your blood type, because you're going to get called back by the blood centers and the blood banks over and over again to donate.

O is the most common.

O is the most common among Caucasians. It's actually the most common among all groups, but a type A is more common in African-Americans than it is in Caucasians.

So we're in the middle of the pandemic. These type of studies come out. What does a patient do with this type of information, and what does a clinician do with this type of information? Is there a disservice that we're consuming some oxygen in terms of talking about this, as opposed to talking about the vaccine, or something else? I just want to be real practical, because you're right. It's interesting cocktail conversation, but what are we going to do about this while we're in the midst of a pandemic?

So, if you're a patient, or if you're just a person who's out there in the community and worried about getting COVID, or if you're a clinician taking care of COVID patients, the simple answer is nothing. What I worry about the most from these kinds of studies, and the fact that they get a significant amount of play in the lay press, is that people will overreact to this study. They'll say Oh, I'm type O, I don't have to wear my mask anymore. Or a clinician could say, well you're type O, I'll send you home from the ED, even though your oxygen level is low. The studies do not suggest that at all.

Right now we don't do anything differently.

Absolutely, nothing different.

Now, for a scientist, it's a clue, that maybe this is something I could study in my laboratory. Maybe there is something there, that it's worthy of study, and that could lead to better understanding of the virus, and our response to the virus, and could ultimately lead to some sort of novel, diagnostic, or treatment. But right now, I would say absolutely nothing should change based on your blood type.

Anything else out there on the horizon that you think may show a correlation or association with COVID-19 that we haven't heard yet?

That we haven't head yet?

Tell us something that we might not be aware of.

I am 100% sure we're going to be hearing about exactly that issue. I know there are research labs around the world that are doing very sophisticated single cell genomic studies, RNA expression studies, on patients with COVID, on survivors, on those who passed away, people with mild disease versus severe disease. We will start to see papers and publications that show certain signatures, perhaps, that predict for better or worse outcomes. In fact, that's how the initial blood story came out, that was based on a genetic association study, that was looking for genes that are associated with risk, and that's where the blood group genes came about.

Looking first, I think, at blood type A, later looking at O. You're in Wisconsin. We see a large number of cases happening in the Midwest. Tell us what you're seeing at your institution.

We're seeing a very significant increase in cases over the last six to eight weeks. We had a relatively mild first wave. It was serious, it was significant, we lost a lot of patients. We had to shut down our clinical operations except for COVID. But unlike the situation in New York, it didn't get so out of control that we had patients in the hallway, and such like that, and then things got better. And by the 4th of July, we were down to a relatively small number of patients in our hospital. But, over the last six to eight weeks, we've seen a steady increase. This morning, I noticed we had about 115, 120 patients in our health system today with COVID. Now, they're doing better. Patients are doing better now than they were in the beginning. We've learned a lot about how to treat the patients, and keep them keeping them out of the ICU, delaying mechanical ventilation, using steroids, using remdesivir, using COVID convalescent plasma. But, we're still seeing way too much COVID, we're seeing way too much COVID in younger people. We're seeing people who are getting a little bit tired of the precautions, and letting their guard down.

Well, Dr. Silverstein, I want to thank you for providing your insights, for helping us understand, how do we interpret some of these studies we might hear in the news or read the paper, and being very practical. What we can, and cannot do with this information. So thanks for giving us that advice.

You're welcome and thanks for inviting me on.

And thank you for watching Coronavirus in Context.