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COVID-19 Update 7/7: Mixing Vaccines & Variant Updates

July 7th, 2021 | 5 min. read

By Steve E. Bishop, M.D.

COVID-19 Update 7/7: Mixing Vaccines & Variants

On this COVID-19 update, Dr. Steven Bishop answers a question about mixing different COVID-19 vaccines right now, discusses vaccinations, and analyzes what's happening with the variants that keep popping up. Watch the full video below and read on for a recap.

Mixing COVID Vaccines

I keep hearing about mixing COVID vaccines. People keep asking about this, and I think it's because of a couple of articles that got posted on Nature and a few other places. The articles showed that, in some small scale studies, there were some potential benefits of mixing COVID vaccines in terms of say, if you got the Pfizer one then you get the J&J one later, or if you got J&J first then get Pfizer or Moderna after that, and that that would enhance your immunity.

And that may be true. And it seems to possibly be true based on the small studies that have been done. Naturally, that's out in the media, and a lot of people are asking questions. Well, does that mean I need to go get a Pfizer vaccine if I got J&J, because I'm worried about this variant or that variant, particularly the Delta variant that's going around that people are concerned about right now?

And my general answer to that question is no, you do not need to do a second type of vaccine. All the vaccines have very good coverage for all of the variants, especially when you're talking about severe disease, hospitalizations, and deaths from COVID, all the vaccines work very well. You do not need to get a second vaccine.

And part of the issue there is that we don't know what the side effect profile is going to be from mixing vaccines, right? It may be perfectly safe to do so, but honestly, we have no idea. And even in the small studies that I was looking at earlier, the side effect rate was higher in people getting their second type of vaccine, even after the first type. So, there is a concern there that the side effects may be more significant, and we just don't know what may happen if you mix vaccines.

I would encourage people to please not do that. Please wait for the studies to come out. If you are concerned about your risk level still after getting an initial vaccine, reach out and talk to your doctor about that and see if that fear is rational, reasonable or not, and what you may need to do to help reduce your risk.

But I don't think that getting a second type of vaccine, at this point, is a good idea because of the safety concerns. We just don't know quite yet. We may know by the fall a little bit more information, but please just do wait on that. I don't think it's a good idea in general to mix the vaccines. So, that's the main topic I wanted to talk about today.

If you guys have questions about that, certainly put those in the comments, but I do just want to encourage everybody that one vaccine is very protective and it's going to do a great job for you. I don't think you need to get a second one. I think you're just exposing yourself to the risks of side effects without a lot of significant benefits. 

Vaccinations Continue

Wanted to briefly touch on the fact that more and more people are getting vaccinated, which is great. And as a result of that, the numbers, in general, are continuing to slowly trend down pretty much all over the place there.

Of course, as always, there are pockets here and there where the numbers are up a little bit or down a little bit, but the US seven day average of fatalities is down to 214, which obviously any is too many, but that's obviously much better than where we were even a month or so ago where we were still running 11,000 cases a day and running around 400, 500 deaths a day.

So, still coming down. Same story in Virginia. And we've now got half the population, half of the total population with at least one vaccine. The big vaccine rollout has happened, and now the continued uptake of the vaccine is sort of slowing down.

There's still plenty of time. Anybody who, as they get into the fall, if you want to get vaccinated, obviously there's plenty of vaccine supply out there, go ahead and get that done if you want to do it.

High-Risk People Should Get Vaccinated

If you're a high-risk person who is still on the fence about the vaccines, I think at this point the data has been out long enough. I'm very comfortable with the safety profile of the vaccines, especially for people who are high-risk, meaning you're over 60, or you have a comorbidity, diabetes, high blood pressure, heart disease, something along those lines.

If you're in those groups of people, I would definitely still continue to strongly encourage you to get vaccinated. If you're younger and healthier, I think that's a little bit more of a sort of you got to do your personal risk calculation, right?

I got vaccinated because it makes sense for me, but it may or may not make sense for you. But I think, on balance, most people will probably find that it makes sense for them to get vaccinated, especially as they get older, forties, fifties, sixties, et cetera.

Younger age groups, I think that, again, it's a personal choice and you got to really balance the risks and the benefits for yourself. But I think most people are still going to come out finding that the risks of the vaccine are pretty low and that it makes sense to get vaccinated for the vast majority of people.

Delta, Lambda, and Other Variants

I have not talked about Lambda, because I haven't seen a whole host of data about Lambda. I think the problem is, like we've talked about before, as long as the virus continues to circulate, we're going to see new variants every few weeks, and that's unfortunately just going to be the case.

The question becomes are they more dangerous or less dangerous? The vast majority of these variants, while they are more often more efficient spreaders, they don't tend to cause worse illness, which is great. It's good that they're not evolving into something that's a more virulent form of COVID.

It's just evolving into something that's more transmissible, which yes is in and of itself a problem. But if all of the high-risk people get vaccinated, all the vaccines seem to protect against all the variants that have popped up in terms of, again, severe illness and mortality. And I think we'll probably find the same thing with this one and all of the other ones that show up.

The reason that this makes sense to me, mechanistically, right, is because the vaccines are mostly targeting the spike protein, which is the protein that the virus uses to attach to the human cell. And if the virus mutates that spike protein more than a certain amount, it's not going to be infectious anymore, it won't bind.

So yes, there's a certain sort of a bell curve, right? The virus can mutate that spike protein somewhat and make changes and maybe make it a little better, a little worse here and there. But if it deviates too much, then the protein will no longer attach to the human cell.

And so, if you've got one of these vaccines that provides pretty good protection against the spike protein, I would expect the vast majority of the variants to be reasonably protected by an antibody response to the spike proteins, even if there are variants here and there. Because the variants can't be but so different before sort of falling apart and no longer attaching to the human cell, in which case they couldn't cause infection at all.

So I expect most of the variants to continue to be well-protected by the vaccine. Who knows. Nature does surprise us, right? Who knows what could happen. But most of the variants, I think you're going to find that the vaccines work just fine for them, barring some very strange thing happening, which certainly could happen.

But based on all the experience we've got so far with getting from Alpha variant to Lambda, they've all still had good protection. So I think we'll keep finding that, hopefully.

I guess the other thing too is to realize that these named variants are just the ones that sort of becoming common enough that they get detected and get cataloged. Every time that the virus enters a human there are probably hundreds or thousands of variants that show up here and there just from the normal virus replication process.

That's just sort of the norm for how these things go. You get thousands of variants all the time when there's an infection. It's just that most of them die off because they don't work, so they just disappear. And the only ones that do work stick around and you see those. So it's sort of a survivorship bias in what you see if that makes sense. 

Steve E. Bishop, M.D.

As a board-certified internist and concierge doctor in Richmond, VA, Dr. Steven Bishop is passionate about helping his patients improve their lives through better health. He helps healthy adults adjust their lifestyles as they age and helps patients with complex medical diseases manage and improve their health.